theunliked :
You will have to do a clean install.
You should look into fixing the graphics glitches though. You'll have to upgrade sooner or later anyway. Remember in 1 year it won't be free and you'll have to buy windows 10. These graphic glitches come from windows update auto updating gpu drivers. Uninstall them and go to manufactures website to install manually.
BTW, what gpu do you have?
''You'll have to upgrade sooner or later anyway''
No I don't think so. Microsoft supports w7 till 2020, five years to come. There is plenty of time. And people are still using XP with no problems at all even after the end of the official support. And at least I want to use stable and working OS instead of a buggy one, even if I had to pay later on.