R15 FixedRig Body Part Textures Not Changing

I am trying to mix two separate bundles to create a unique character design for my game, however, whenever I change the mesh and texture ID of either lower arms, lower legs, hands, or feet, only the mesh changes and texture stays the same.

Is there anyway to have unique textures on R15 rig parts without changing the upper arms or upper legs?

For reference, the two bundles I am trying to mix are Lord Griswold - Roblox and Zombie Left Arm - Roblox.


I haven’t found an actual solution to this problem, but I’ve made a work around my combining the textures in Paint.NET and then uploading them to Roblox.