Leonie, I'd really like to apologise for being rude to you. I mean it, honestly.
In a professional environment I would assume that one first assures that the base to be dealt with is clear. Meaning, one knows exactly what OS and Photos app version the original question is related to, so everybody talks of the same thing. But as no one of you supporters even asked that question, I assume, that you already knew from following other discussion threads that this problem has nothing to do with the OS X version at all. But then why hassle me for just indicating my OS X version? Was this necessary? I didn't even ask for support here, nor did I raise a question. I was simply stating my version in addition and actually, you probably use the very same Photos app version then I do (because it did not change since 10.11.4 yet). My only intention was to let the originator of the message know, he's not alone with that problem.
Now to Larry Something, you remember me of that namesake under MS-DOS, you know, when the Mac's had already 3D graphics displayed. But maybe your own advise in this tread is useful .... keep trying.