If you are not comfortable in multi-tasking while playing, you can just reset your screen resolution to 640x480 to enable a change of screen size. You can access this by right-clicking on your screen and clicking the Property tab. From there, you will select the Compatibility Tab and then the Display Settings. Afterwards, you will find the different resolution setting. Just choose the one that you want to resize the screen.
How can I rotate my screen to adjust to some games?
With the capabilities of No$GBA itself, this is not possible. However, there are already some utilities that can enable you to perform such action. Some of the utilities that you can use are No$Zoomer, NDS2XGL2, and NOZ.
Can make No$GBA play games in full screen mode - YES. How to make No$GBA larger screen - red the instructions here. No$GBA screen size can be changed with a help of Zoomer or X2 utility. The easy way to get No$GBA stretch screen is by installing WinDS PRO DSi emulator package that contains the tools needed to make No$GBA screen bigger or resize small window to a biger one. No$GBA screen zoom and rotate screen options.
I want to make the screen bigger. How can I do it in No$GBA?
Changing the screen size of your NoGBA emulator would be quite difficult since this certain feature is currently available only for the GBA mode. Still, this will not be quite a problem since there are already many third party applications that can change the screen of your NoGBA. For example, you can use the application NDS2Xgl in some cases. '