I want to change the material of the cushion of the chair but when i try to edit it, i changes the whole chair. Anyone knows what I can do?
The materials and textures are assigned to the parts/faces of the mesh in the actual asset itself. Unreal basically exposes those material ‘slots’ to you in the editor to switch out. If you want to change which faces of the mesh the materials are applied to, the best way to do it is change them in a 3d editor like Blender, 3ds, Maya, etc. Blender is free and there are a hundred youtube tutorials for this exact thing.
Export fbx from Unreal:
Import fbx to Blender:
Applying materials to faces in Blender:
Reread the question and thought about it for a minute, its also possible you have a single texture on there that covers the whole mesh. Like part of the texture is the cushion, part of it is the legs, etc. You can export the texture, open it up in photoshop or GIMP and just edit the part of the texture that handles the cushion, then reimport it.