Need some help regarding the assembly of my MK2S and the quality of my prints  

Hello,

I own a Prusa i3 MK2S that I had built myself. Now I am pretty new to 3D printing as a whole so I'm sure I made a mistake or 2 when building it. I'm hoping someone can help me.

So the overall problem seems to be that no matter the layer height (I print at 0.10 - 0.15mm on average), I get pretty obvious lines on all of my prints, and the quality seems to be worse than that of when I put it in PrusaSlicer. On top of this, I constantly get a pretty bad amount of stringing on all of my prints, particularly if I'm printing multiple things at a time there's a web of material between them. The quality of the print is substantially more noticeable on larger prints, and the stringing is much worse on the smaller prints.

I've tried correcting the stringing by lowering the heat of my nozzle 5-10 degrees, as well as by tightening the two little bolts that push the filament through the extruder to no avail. Furthermore, I believe I didn't align my bed rails properly (I believe it's the Y-axis?). When my printer bed gets to its furthest-most point (the top of the axis) it makes a lot of noise.

So before I disassemble some of my printer to fix things I wanted to ask; what's the best way to fix the quality and stringing? I'm assuming it's a hardware issue because nothing I've changed in PrusaSlicer seems to make much of a difference. Additionally, what's the easiest way to ensure the my print bed is well aligned so I don't put it back together only to find I've done it wrong again?

I can provide pictures of prints with print specs if need be.

Thank you in advance!

EDIT: The material I'm using is 1.75mm PLA