After having made the changes in your Studio template, the big thing is to click "Save and publish" before going into Creative manager.
I assume you now have clicked "Save and publish" in Studio otherwise you are a true rebel that no law can hold back and these next few steps will need you to do some Jedi mind games. Start by going into your Campaign overview and;
Go to the Creative Set your need to update where you will see a yellow top line indicating a pending design update
Over over your Creative set and click the 3 little dots
Click on "Update design"
In the update view you will be able to go through your formats on your left hand to see a before and after as well as formats added or deleted. Then when you have checked the updates are correct:
Click off the new formats under "Template Updates" you want added to the Creative set
Choose "ignore for now" or "Accept Updates" in your bottom right corner
Now your Creative set is updated, ready to be exported or if you are one of the lucky who host through Zuuvi then the changes will be pushed to the live creatives! 🤠