After taking an exam and shutting my computer down this morning, I turned it back on later to find my background was black. When I went to change it, I found it was unchangeable and it said "Some of these settings are hidden or managed by your organization".
I saw another forum post that said to make another profile to see if it was the same for that and it was not the same - I was able to change the background on the other profile. I have attached a screenshot.
Thank you!