When I click into lightroom under the develop tabe it goes into fullscreen.

[nocturnetouch]

How do I go back to the regular develop module? Only when I click out of light room does it go back to the normal view. When I click back inside it goes to this weird fullscreen mode I can't get out of this mode no matter what I click or what normal key combination for altering the view I press.  Version 10.4 2021

[Rikk Flohr: Photography · Accepted solution]

You've activated a second screen. Command/Control + F11 should close this. 

[nocturnetouch]

That was the issue. F11 was correct. Thank you for your reply.