Remote Desktop doesn't maximize to fullscreen

"Try CTRL+ALT+BREAK - which switches the client between full-screen mode and window mode.
That should put you back in full screen mode.
In case the BREAK key isn't available, try one of these key combinations:

CTRL+ALT+PAUSE
CTRL+ALT+PRTSCN
CTRL+ALT+FN+SCRLK

Reference: Remote Desktop Services Shortcut Keys"

"This is a known issue with systems running Windows 7 / Server 2008 R2 whose resolution is set at 1366×768. Microsoft has created a hotfix which you can read about / request here:

Remote desktop is not displayed in Full-Screen mode when the screen resolution is 1366× 768 pixels in Windows 7 or in Windows Server 2008 R2

If you're lazy or don't want to give MS your email, you can just download it from here. Just know that by doing so Microsoft will have no way of notifying you if there is a recall on the fix."

"I am Using Dell Latitude E5450 Laptop with windows 7.
Ctrl + Alt + Fn + B worked for me."

"I resolved a similar problem. I am using Windows 10 and RDPing into a Linux box. Setting my RDP to full screen mode and having the session maximized did not prevent horizontal and vertical scroll bars from appearing. To get rid of these bars, I saved my RDP connection settings by pressing Save As... on the first tab of the configuration. Then, I opened the saved *.rdp file in a text editor (Notepad or Wordpad will work.) I then added this line to the top of the file, saved it and used this .rdp file to successfully log in without scroll bars:

smart sizing:i:1"

I've also seen users not being able to maximize because of the Screen setting "Use multiple monitors for this connection" - when this is checked, the Full screen slider remains locked.