@spacemanspiffy at a glance, it looks like you're doing a lot of instantiation in your ui scenes. If it works for you, keep it up, but in my experience I've found ui to be a lot easier if you centralize your main menu and derivative menus (settings, credits, level select, etc...), and just toggle show() and hide() on the relevant control nodes to handle navigation. Also if you haven't yet, definitely look at scene-unique names (https://docs.godotengine.org/en/stable/tutorials/scripting/scene/_unique/_nodes.html). They make for really really clean structures.

@spacemanspiffy for sure :)