Edit arm segments in blank puppet

I'm trying to add t-shirt sleeves to the upper arm segments of a blank puppet by editing the sculpt but it seems like I can't spraypaint (yes I made sure the tint is all the way down) and I'm not even sure what's happening to be honest. Somehow the only colours I can get are greys, but messing with the tweak menu sliders for the sculpt never give me the colour I want. So instead I tried to add to the sculpt in the color of the sleeve but I get the exact same problem.
Okay, so I figure I'll just make a new sculpt and attach it to the arm segment, but nope, I can't scope into the upper arm segment on its own, so the sleeve doesn't stay exactly in place when the puppet is moving. I tried turning off movable, collidable, and gravity and the sleeve still wobbles around when walking.
Any help, or insight on why only the arms and legs behave this way, would be greatly appreciated!