Dialogue Box too small-Windows 10

[dragon8]

When I download a photo from the internet, the dialogue box to save the photo is only 1/4 of the screen.
Also, when I open the recycle bin, the dialogue box is only 1/2 of the screen.
I use the cursor to expand the dialogue box to full screen, but this only works temporarily. When I turn my pc on the next time, the dialogue box problem occurs again.
Any suggestions on how to have the dialogue box open to full screen permanently?

 

[Wulffz]

Check your windows monitor settings for your resolution. You might have a weird scaling setting wrong.

 

[dragon8]

Wulffz:

Thanks for the reply.
So what should the monitor's correct resolution setting be?