LT Spice XVII is in my opinion a little weird about the simulation command pull-down menus. So people wind up editing sim command lines to insert and delete semicolons to enable various sims. I switch other kinds of Spice directives on and off by right-clicking and changing the line from "spice directive" to "comment", which is easier than editing semicolons.
I emailed Mike Engelhardt about that and he pointed out that you can switch a sim directive line to/from a comment line using ctrl/rightclick. I didn't know that.
Ctrl/rightclick works for all the comment/directive cases.