diff --git a/eeschema/dialogs/dialog_lib_symbol_properties.cpp b/eeschema/dialogs/dialog_lib_symbol_properties.cpp
index 4ad57ab291..40bd4f64b2 100644
--- a/eeschema/dialogs/dialog_lib_symbol_properties.cpp
+++ b/eeschema/dialogs/dialog_lib_symbol_properties.cpp
@@ -172,7 +172,7 @@ bool DIALOG_LIB_SYMBOL_PROPERTIES::TransferDataToWindow()
     m_DescCtrl->SetValue( m_libEntry->GetDescription() );
     m_KeywordCtrl->SetValue( m_libEntry->GetKeyWords() );
     m_SelNumberOfUnits->SetValue( m_libEntry->GetUnitCount() );
-    m_OptionPartsLocked->SetValue( m_libEntry->UnitsLocked() && m_libEntry->GetUnitCount() > 1 );
+    m_OptionPartsInterchangeable->SetValue( !m_libEntry->UnitsLocked() || m_libEntry->GetUnitCount() == 1 );
     m_AsConvertButt->SetValue( m_libEntry->HasConversion() );
     m_OptionPower->SetValue( m_libEntry->IsPower() );
     m_excludeFromBomCheckBox->SetValue( !m_libEntry->GetIncludeInBom() );
@@ -359,7 +359,7 @@ bool DIALOG_LIB_SYMBOL_PROPERTIES::TransferDataFromWindow()
     m_libEntry->SetDescription( m_DescCtrl->GetValue() );
     m_libEntry->SetKeyWords( m_KeywordCtrl->GetValue() );
     m_libEntry->SetUnitCount( m_SelNumberOfUnits->GetValue() );
-    m_libEntry->LockUnits( m_libEntry->GetUnitCount() > 1 && m_OptionPartsLocked->GetValue() );
+    m_libEntry->LockUnits( m_libEntry->GetUnitCount() > 1 && !m_OptionPartsInterchangeable->GetValue() );
     m_libEntry->SetConversion( m_AsConvertButt->GetValue() );
 
     if( m_OptionPower->GetValue() )
@@ -676,7 +676,7 @@ void DIALOG_LIB_SYMBOL_PROPERTIES::adjustGridColumns( int aWidth )
 
 void DIALOG_LIB_SYMBOL_PROPERTIES::OnUpdateUI( wxUpdateUIEvent& event )
 {
-    m_OptionPartsLocked->Enable( m_SelNumberOfUnits->GetValue() > 1 );
+    m_OptionPartsInterchangeable->Enable( m_SelNumberOfUnits->GetValue() > 1 );
     m_pinNameOffset.Enable( m_PinsNameInsideButt->GetValue() );
 
     if( m_grid->IsCellEditControlShown() )
diff --git a/eeschema/dialogs/dialog_lib_symbol_properties_base.cpp b/eeschema/dialogs/dialog_lib_symbol_properties_base.cpp
index d444607e3f..762cad72fe 100644
--- a/eeschema/dialogs/dialog_lib_symbol_properties_base.cpp
+++ b/eeschema/dialogs/dialog_lib_symbol_properties_base.cpp
@@ -1,5 +1,5 @@
 ///////////////////////////////////////////////////////////////////////////
-// C++ code generated with wxFormBuilder (version 3.9.0 Nov  1 2020)
+// C++ code generated with wxFormBuilder (version 3.9.0 Dec 30 2020)
 // http://www.wxformbuilder.org/
 //
 // PLEASE DO *NOT* EDIT THIS FILE!
@@ -52,7 +52,6 @@ DIALOG_LIB_SYMBOL_PROPERTIES_BASE::DIALOG_LIB_SYMBOL_PROPERTIES_BASE( wxWindow*
 	m_grid->SetColSize( 10, 84 );
 	m_grid->EnableDragColMove( false );
 	m_grid->EnableDragColSize( true );
-	m_grid->SetColLabelSize( 22 );
 	m_grid->SetColLabelValue( 0, _("Name") );
 	m_grid->SetColLabelValue( 1, _("Value") );
 	m_grid->SetColLabelValue( 2, _("Show") );
@@ -64,6 +63,7 @@ DIALOG_LIB_SYMBOL_PROPERTIES_BASE::DIALOG_LIB_SYMBOL_PROPERTIES_BASE( wxWindow*
 	m_grid->SetColLabelValue( 8, _("Orientation") );
 	m_grid->SetColLabelValue( 9, _("X Position") );
 	m_grid->SetColLabelValue( 10, _("Y Position") );
+	m_grid->SetColLabelSize( 22 );
 	m_grid->SetColLabelAlignment( wxALIGN_CENTER, wxALIGN_CENTER );
 
 	// Rows
@@ -196,10 +196,10 @@ DIALOG_LIB_SYMBOL_PROPERTIES_BASE::DIALOG_LIB_SYMBOL_PROPERTIES_BASE( wxWindow*
 
 	sbSizerSymbol->Add( bSizerUnitCount, 1, wxEXPAND|wxLEFT|wxTOP, 5 );
 
-	m_OptionPartsLocked = new wxCheckBox( sbSizerSymbol->GetStaticBox(), wxID_ANY, _("All units are not interchangeable"), wxDefaultPosition, wxDefaultSize, 0 );
-	m_OptionPartsLocked->SetToolTip( _("Check this option to allow symbols with multiple units to have different\nelements.  Uncheck this option when all symbol units are identical except\nfor pin numbers.") );
+	m_OptionPartsInterchangeable = new wxCheckBox( sbSizerSymbol->GetStaticBox(), wxID_ANY, _("All units are interchangeable"), wxDefaultPosition, wxDefaultSize, 0 );
+	m_OptionPartsInterchangeable->SetToolTip( _("Check this option when all symbol units are identical except\nfor pin numbers.") );
 
-	sbSizerSymbol->Add( m_OptionPartsLocked, 0, wxALL, 5 );
+	sbSizerSymbol->Add( m_OptionPartsInterchangeable, 0, wxALL, 5 );
 
 
 	bSizerLeftCol->Add( sbSizerSymbol, 0, wxEXPAND|wxALL, 5 );
diff --git a/eeschema/dialogs/dialog_lib_symbol_properties_base.fbp b/eeschema/dialogs/dialog_lib_symbol_properties_base.fbp
index 9184db2cf2..2daa54d939 100644
--- a/eeschema/dialogs/dialog_lib_symbol_properties_base.fbp
+++ b/eeschema/dialogs/dialog_lib_symbol_properties_base.fbp
@@ -1593,7 +1593,7 @@
                                                                             <property name="gripper">0</property>
                                                                             <property name="hidden">0</property>
                                                                             <property name="id">wxID_ANY</property>
-                                                                            <property name="label">All units are not interchangeable</property>
+                                                                            <property name="label">All units are interchangeable</property>
                                                                             <property name="max_size"></property>
                                                                             <property name="maximize_button">0</property>
                                                                             <property name="maximum_size"></property>
@@ -1601,7 +1601,7 @@
                                                                             <property name="minimize_button">0</property>
                                                                             <property name="minimum_size"></property>
                                                                             <property name="moveable">1</property>
-                                                                            <property name="name">m_OptionPartsLocked</property>
+                                                                            <property name="name">m_OptionPartsInterchangeable</property>
                                                                             <property name="pane_border">1</property>
                                                                             <property name="pane_position"></property>
                                                                             <property name="pane_size"></property>
@@ -1614,7 +1614,7 @@
                                                                             <property name="style"></property>
                                                                             <property name="subclass"></property>
                                                                             <property name="toolbar_pane">0</property>
-                                                                            <property name="tooltip">Check this option to allow symbols with multiple units to have different&#x0A;elements.  Uncheck this option when all symbol units are identical except&#x0A;for pin numbers.</property>
+                                                                            <property name="tooltip">Check this option when all symbol units are identical except&#x0A;for pin numbers.</property>
                                                                             <property name="validator_data_type"></property>
                                                                             <property name="validator_style">wxFILTER_NONE</property>
                                                                             <property name="validator_type">wxDefaultValidator</property>
diff --git a/eeschema/dialogs/dialog_lib_symbol_properties_base.h b/eeschema/dialogs/dialog_lib_symbol_properties_base.h
index af4156d8c8..4d1d5f7c8a 100644
--- a/eeschema/dialogs/dialog_lib_symbol_properties_base.h
+++ b/eeschema/dialogs/dialog_lib_symbol_properties_base.h
@@ -1,5 +1,5 @@
 ///////////////////////////////////////////////////////////////////////////
-// C++ code generated with wxFormBuilder (version 3.9.0 Nov  1 2020)
+// C++ code generated with wxFormBuilder (version 3.9.0 Dec 30 2020)
 // http://www.wxformbuilder.org/
 //
 // PLEASE DO *NOT* EDIT THIS FILE!
@@ -69,7 +69,7 @@ class DIALOG_LIB_SYMBOL_PROPERTIES_BASE : public DIALOG_SHIM
 		wxCheckBox* m_excludeFromBoardCheckBox;
 		wxStaticText* m_staticTextNbUnits;
 		wxSpinCtrl* m_SelNumberOfUnits;
-		wxCheckBox* m_OptionPartsLocked;
+		wxCheckBox* m_OptionPartsInterchangeable;
 		wxCheckBox* m_ShowPinNumButt;
 		wxCheckBox* m_ShowPinNameButt;
 		wxCheckBox* m_PinsNameInsideButt;
@@ -87,7 +87,7 @@ class DIALOG_LIB_SYMBOL_PROPERTIES_BASE : public DIALOG_SHIM
 		wxButton* m_stdSizerButtonOK;
 		wxButton* m_stdSizerButtonCancel;
 
-		// Virtual event handlers, overide them in your derived class
+		// Virtual event handlers, override them in your derived class
 		virtual void OnUpdateUI( wxUpdateUIEvent& event ) { event.Skip(); }
 		virtual void OnSizeGrid( wxSizeEvent& event ) { event.Skip(); }
 		virtual void OnAddField( wxCommandEvent& event ) { event.Skip(); }