Skin Resets to a Non-Custom Skin on Launch

Every time I launch my game of Minecraft my Skin always sets to a default non-custom skin and its free out of a pack.  I go to Change my Skin to a custom one and it all works perfectly. Unless I go to restart Minecraft for some Tests that I want to do. Yes, it's not such a big deal having to change it every time but it kind of wastes time a bit. On my Phone and My PC I switch it to the same skin because I linked them both and it still doesn't work when I restart both versions.