sorry about my english, i not always ready to here, this video for answer my friends about her problem xixixixi.
segment:
00:00 introduction about problem
00:34 demonstrate make problem to 500%
00:50 display setting
01:02 restart pc
01:07 basic problem
01:25 how to fixed in back
01:45 click display setting
01:56 click black or main content
2:10 scroll down menu
2:20 look at turn of custom scaling and signout
2:33 signout automatic and restart
2:35 now your desktop is back to normal