Did my first ever build now I'm down to the part where I need to tune it. I really need this done because I'll have a recon + impt group ride

My chain cannot shift up (or lower gears). It's stuck on the 6th. I checked and alignment and it's fine. The chain dances cha-cha from 7th to 6th and doesn't wanna "commit" to the 7th cog (I have yet to put the cables for the FD but I adjusted the screws so that there's no rub when I'm on my smaller chain).

the culprit: the low/high tension screws are screwed all the way in (YES I KNOW). Now to me, if I move either screws it'll go mis-aligned.

How do I adjust it so that I can still turn my screws and it eventually lines up to the 7,8,9 and 10th cog? or how do I get back to a "starting point" where I can play with the screws and eventually work my way until the 10th cog to align it properly?

Thanks.