Selection start & end points won't stay put

I use Audacity 2.1.3 with Windows 10.

When I set the Selection start & end points in the toolbar at the bottom, not by clicking & dragging on the track (e.g. Start = 1m00sec, End = 1m30sec), then click on a point within that selection, the Start & End points change to the audio position where I clicked (e.g., 1m20sec). How can I, when desired, essentially lock the selection start & end points?

Audacity does not have IN and OUT edit points like you may be used to in video editors. It does have Labels.