Merging Meshes without reverting Collision Complexity back to default

Hey, I’m working on a map, and I keep adding new elements every now and then. It’s kind of annoying because whenever I merge the meshes together, it reverts the collision complexity back to ‘‘default’’. Well, some of the meshes anyways, some do keep the assigned collision complexity and this is great, but some others just keep reverting back to default?

I’m probably missing a something, but I really don’t know what, help?