How to set the default hostname in category builder?

Every time I open the category builder, it shows an error due to unknown hostname. I need to manually select the hostname. How to set my hostname as the default or remove unknown from the list?

Look into “raw data” and delete all buckets with unknown hostname.

There is a bug with the stopwatch feature that needs to be addressed for this: https://github.com/ActivityWatch/activitywatch/issues/1097#issuecomment-2687911846