You must first check the checkbox in the Simulation Command dialog,
after which the signals will appear in the User Defined Signals
autocomplete lists.
Adds maximum step size setting used by transient analysis solver,
and 'use initial conditions (uic)' setting. Enabling uic disables
DC operating point analysis and may introduce singularities. It requires
a careful selection of initial conditions of circuit elements.
Fixes https://gitlab.com/kicad/code/kicad/issues/2515