OR, .. you can press [F6], which turns off Commander names, and you can select squads by clicking. (no need for LMB and drag).

Yes, but it's a units, not a squads.
Oops sorry, I meant units.
I saw that you said
squads in your post, which confused me at first, as I thought you meant selecting a squad by clicking in window, which obviously you don't.

Squad selection by division panel,
or, LMB & drag in window.

Unit selection by division panel,
or LMB in window.

I think we're getting there.

Cheers
Tom