Changes I’ve made to my site only show when i’m logged in. According to various other threads it seems to be a problem with cache, however, i’ve completely deactivated my W3 cache plugin, and the problem still isn’t resolved.
This does indeed sound like a cache problem. Plugins on the server side will cache the site for faster serving, while your own browser does its own caching to not have to repeatedly download the same web content.
In WordPress, any caching plugin should have a “clear cache” button, and your browser cache should have a setting for deleting cache.
If you develop with your browser’s developer tools open, your browser shouldn’t cache.