Does anyone know how to make a hat stay on the head?[Solved]

hi, welcome to the forums!

Here's a tutorial for weight transfer.

In your particular case, you only need one bone that is the head one. But i suggest you reading the tutorial anywhere for future reference.

In edit mode, you need to head over the Object data tab (upside down triangle) and add the head bone to the list of vertex groups by clicking the + button and writing down the bone name. Then select all the mesh by hovering the mesh with your cursor and pressing A so that everything is orange. After this select the bone you added and click on "assign".



You can look for the name of the bones by enabling the rig (from the groups list, the rig has to have the little eye and arrow on white so that you can select the it). Select the rig group, change to pose mode and head over to the little bone tab. From there, whenever you click a bone, you'll see it's name on the tab. You can select the text and copy the name from there.