It’s easy as searching for your microwave model + the keyword “manual”, there’s typically a section on exactly this. If nothing comes up just try a generic search like “How to silence microwave” and find what works.
FYI some microwaves do not have a silence function
This seems to be the main issues with his apps. Visibility is scarce beyond the original post, wherein even with followers the chances of someone seeing your post beyond that honeymoon phase dwindles.
The only exception are users with lots of followers. From what I’ve seen in my brief time using Pixelfed for example, it’s usually accounts with at least a few hundred followers that see a highet retention of visibility.