I’m still new to the forums so I apologize if someone’s already solved this issue, I might just be using the wrong search queries but I’ve watched enough video tutorials to pick up that what’s happening shouldn’t be happening. I’d dig deeper but I only have limited terminology under my belt to help me.
As part of a rigging class assignment we were given a premodeled character to rig and skin. I’ve followed the professor’s notes to the best of my ability, even consulted internet sources where things became unclear and up until now have resolved things just fine.
I got to about the part where I smooth bind the character (as per the instructions in my notes, the prof even gave us screenshots of what the weighting should look like mid paintjob), and if it helps these are the settings I’m using

Previously I was unable to paint on the mesh at all, until a couple of sites recommended things like unchecking ‘remove unused resources’ and ‘maintain max influences’. That and exporting the model to a new scene seemed to resolve the issue where I got a red X when trying to weight paint and the black & white (is it called a heat map?) never showed up.
Now I’m noticing that what I try to paint weights on anything, the black & white shows up but the painted mesh seems to detach from the bone and go back to how it was in bind pose. The only time it worked as it should’ve was when I tried to paint the elbow so I wouldn’t lose so much volume when the joint bent. Everything else, here’s what happened…

As for the brush settings, the tutorials I looked at say to use ‘add’ but this was the result.
I was nearly done he assignment on Sunday night but this has caused me to go over the deadline by a day (as of this writing). I’m going to contact the professor anyway and ask if I can send him what I have and resubmit later, but I still want to know what went on here so it doesn’t pop up when I rig my next model. I like rigging, I just with I was a better self troubleshooter if that makes any sense
Much appreciated,
-Niki