For New Projects, I suggest creating a Custom Template. A Template can contain All of your desired settings. Here’s a link to an older Tutorial but, is basically still valid.
For Existing Projects, there are a couple of ways to change Selected or All of the files but, given that you may have many files in different locations, it could be a lot of work.
If I needed to do something like 'Changing items, such as layer/other parameters in many files I would do it via Coding a Utility Application. In fact, I just did this last week for fixing All of the my .mod Footprint Files that went south when upgrading Kicad to 7.0.7
For a Coder, it’s quite simple, it amounts to nothing more than doing a Search & Replace and doing it in Python, I used the ‘os.walk’ to walk through the Directory/Folder’s to make Bulk Changes. But, not knowing exactly what item(s) you want to change, I can’t say if doing it will be simple or not… depends.
As an Aid to efficiency, I made it into a Stand-Alone App containing an Editable default Replace String… It will do One String/Text change on All ‘same strings/text’ in Multiple files in the DIR and it’s Sub-Dir’s.
If wanting to change many Different Strings/Texts, just need to embed them into the Code…
This is what mine looks like
