Hi Norman,
the publish changes button should appear if the CMS finds that you (the user account in which you're logged in) have made (and saved, if you changed e.g. component properties) changes to the channel you're currently looking at. So, if you don't see the button, there could be multiple reasons. Can you check if
- there are changes
- the changes have been saved
- the user account matches
If this doesn't help, pease tell us what kind of a change you made that doesn't trigger the publish button. (I believe that, in 10.2.x, changes to the Channel Settings would take immediate effect, so that could be the reason for having no Publish button).
HTH
Tobi