How to change template for existing assembly ?

How to change template for existing assembly ? -drwdot-file format-

At the moment main assemblys BOM doesn't update because it's linked to specify template. Same problem with parts. 

Template also has all of the settings i would like to use when working with the file. 

Could not find the answer via internet. I use Solidworks 2020.

SolidworksModeling And Assemblies