I have also turned on debug and noticed I do get a lot of errors.
Don't enable debug_output if you have no idea what it is and if a supporter hasn't asked for it to be turned on. Leave notices_display turned off at all times - it's a developer-only feature (as suggested in the docs). As the name suggests, it doesn't display errors, but notices, which is an entirely different animal. Developers use it during design and bug-hunting stages. End users like you shouldn't enable it at all. Your report sound a bit like a bad joke where a man sees his doctor and complains "whenever I hit myself on the head, it hurts badly". Doctor's advice of course is: "don't hit yourself on the head in the first place"!
I also noticed with 1.4.5 an unregistered user could see all thumbnails but had to register to see anything else. Now an unregistered user can see intermediate pictures as well. I don't see anyway to change this other than set it so you have to register to see anything. I don't really want to do it that way liked it where you could view thumbnails but had to register to see intermediate and full size pictures.
That's nonsense - this has never been a feature of cpg1.4.5. You must have applied the hack suggested in
http://coppermine-gallery.net/demo/cpg14x/docs/faq.htm#viewThumbnailsOnly to your cpg1.4.5 gallery. When upgrading, the hack was of course lost - if you need it, you'll have to re-apply it to the cpg1.4.10 core code again. However, this issue is in no way related to your initial issue; we have a strict "one question per thread" policy that you agreed to respect when signing up. Do so in the future - don't post various issues in one thread. You even reported various issues in your initial posting, which is wrong in the first place.
Both your irrelevant report about notices surprisingly displaying when the corresponding option is enabled in coppermine's config as well as your report about a missing feature that you have hacked into coppermine before makes it more likely in my opinion that regarding this thread's initial issue the error is on your end (PEBCAK issue).
If I do a search the search finds the files I am looking for and displays the thumbnails.
Provide a search term to search for.
If I am viewing a picture and click on add to favorites I get The selected album/file does not exist !
Confirmed. Would have moved this thread to the bugs board for further investigation, as it happens on the demo as well. However, as this thread is too much cluttered already, I won't.
If I click on user mode I get leaving admin mode then it returns back to where it was
As suggested: never leave admin mode if you have no idea what user mode is meant to be used for.