I have no idea how to try out the photo but will check it now.

You should see that posts with images have an icon display in the top corner - if you click on the image, it should now open in a new tab.

The problem is solved on the phone but not on the the computer/laptop

I suspect that's just a coincidence - the fix was unrelated to the type of device being used.

It's possible that you're experiencing this issue when switching between accounts. If you open the post with an account that doesn't have the correct role, and then log in with one that does, you'll need to refresh the page before the admin options will appear (which is why going to the community and back will work).

Thanks for taking a look - I wish I'd done the slider fix last year!