Can I find average amplitude over a section of a track?

normalizing

A note to be careful of your naming. “Normalizing” and “RMS Normalizing” are very different tools.

Are you following the ACX Mastering Suite 4?

Also there’s a note that selecting the whole timeline by clicking just above MUTE doesn’t work in Audacity 2.2.0. Double click the track itself.

Koz