multitrack keeps shifting to waveform

Normally it takes a double-click for this to happen - that's the way it's intended to work. The chances are that this is a mouse or touchpad setting you need to look at, to stop it generating a double-click when you've only given it a single one. Not all mice have the same control options so it's hard to be any more specific about this, but I'm reasonably confident that this is what you need to investigate, as there's nothing I can find in Audition's Preferences that will affect this.

You might also want to have a look at this page about mouse settings.