I've had this problem for a while, and it's a minor but persistent annoyance and time sink.
 
So, Export settings now persist with the project, since that change a while back. If you export from one project as mp3, next time, it remembers that setting. Or if you export as 32 bit wav, then next time it remembers that setting.
 
However, I can never get Stereo / Mono to stick. No matter what, that option always goes to the same as the last export of *any* project. So if I export as Stereo, and load up a different project that I know was last exported as mono, the option will be forced to Stereo.
 
Anyone encountered this? Am I doing something wrong?

I created an export preset and it persists from project to project, not globally.

Just tested.
We have a lot of digitazing projects and made export-presets.
When you save Stereo or Mono within an export-preset, then SONAR remembers for every project the last used preset.  It remebers also Stereo or Mono.
Sonar saves for every project his own export preset.

Yeah, I think it's something odd about my installation maybe. Just can't make it stick.