animation and rigging

I made a model for a game I’m working on and I wanted to rig and animate it, but after much time working on it, I’ve all but given up. Its essentially composed of many different parts, clothes, body, etc… when I add an armature and start taking different approaches the weight gets all messed up and then things begin to not work right. I’ve heard about rigify, but after following a couple tutorials I’m even more lost than I was with other methods. This is whats been happening. I skinned it pretty good, so idk whats up

It looks like the forearm mesh is weighted to the forearm.R bone, but also weighted to a parent bone or bones, upper_arm.R for example, or maybe some of the body or leg bones.
With the armature set to Pose Mode, I would suggest switching the mesh to Weight Paint Mode, then selecting different pose bones, check the weight on the forearm mesh with different pose bones selected (RMB).
With the mesh in edit mode, weight can be assigned to or removed from the selected vertices, for each vertex group, via the Vertex Groups panel, Properties > Mesh > Vertex Groups.