I'm running two monitors on a MAC OS. LR, with it's control panels will randomly switch to the other (smaller #2) monitor. The only way I can get it to go back is to quit and re-start LR. Any one have a similar experience or an answer?
We would recommend you to update the Lightroom software 2015.4 and then try it out. refer: Lightroom CC 2015.4 / 6.4 now available
Also, If the above step didn't help then try turning off the Graphics Processor from the Lightroom preferences.
Go to Lightroom Preferences from the Edit menu
Click on Performance tab
Uncheck the Graphics Processor
Let us know if that helps.