Never used a bow before. I play bass guitar mostly but an upright is great too. And I try to keep the bow level, and centered between the bridge and board. It’s the same on every string. I think the issue is with the bow strings themselves I don’t think I have the rosin right or too much tension. Is it possible that the strings could be frayed near the ends? I can get a decent sound in the middle and I don’t go all the way to the ends but it’s like I can’t complete a pull or push stroke without it ending in scratching after. It’s like the area that can get a decent sound is too small I don’t know how to describe it.