Unable to change theme on subdomain without it effecting entire site

Ok.. I think I may have figured it out. I had mapped the subdomains when I set-up the multisite and I dont think I was supposed to..

I started a new test site (subdomain) where I did not use the domain mapping. It seems to be working how I want the subdomains to work where I can change the theme and header.
I also deleted the mapping of the other 2 subdomains I had set-up, cleared cache but they are still showing the same results when I try to change the header or theme.
So I guess I will just delete them entirely & then set them up again but not map them?
Am I right with this being the reason for my issue? Do I need to map my subdomains? I dont want to change the name of them. I have my main site as site.com then the subdomains as username.site.com. Users will only have subscriber access to the rest of the blogs on the network and editor access to their blog (subdomain). I will be pulling the most recent blog posts from all of the blogs to the main site using a plugin and will also have 2 pages on the main site(calendar & photo) that the user can contribute to (and I can allow access using a plugin for that as well).

Can someone PLEASE give me feedback? I have searched for a way to contact wp for support and am unable to find anything so if there is another way to get help please point me in that direction.
Thanks.

Or should I keep the domain mapping and check
Remote Login – Means that logging in to one site will log you in to all sites.
and
Disable primary domain check – Means that multiple domains pointing to a single site will be treated as separate sites, instead of redirecting all domains to the noted primary domain (not recommended).

i am so confused…

The author of a plugin called “Simple User Profile” just did some work for me, truly knows what he is doing and can help you. If you wish, look him up and say “Hi!” from me.

leejosepho, thank you so much! I will try to find him and see if he can help ??

https://www.whereyoursolutionis.com/

“Do I need to map my subdomains?” In a word – no.

“I will just delete them entirely & then set them up again.” Whoa. Delete the extra files yes. But adding sites to a multisite network does not require installing anything else. Add a site under the Network->Sites menu and away you go – start blogging. No need to upload files or “set-up” anything else.

Can you follow the directions for adding the wildcard subdomains? If you can’t do wildcards, then subdirs is simpler – IMHO. Less confusing for me.

My multisite network for example has 400+ sites – but is still just one instance of WP files. One “wp-config.php” in one directory, one database. It sounds like you have a jumble with two(or more) instances of WP using the same database.

The “subdomains” of a multisite are virtual, you will not see “subdomain folders” via ftp like you are describing.

https://codex.www.ads-software.com/Create_A_Network

“WordPress must be installed in the root of your webfolder (i.e. public_html) for subdomains to work correctly. They will not work from within a subdirectory.”

Yes I can follow directions.. I followed the codex directions when I set-up the network (and also the otto directions) but I set them up where I did the wildcard and the domain mapping.
Everything was fine until I tried to change the header on a subdomain. When I changed it, the header that was showing on the entire site changed. I began searching to see if I was able to change the header on a subdomain- meanwhile asked on here if I could and was told yes-change it through appearance. I went by that answer b/c any clear answer I found was outdated by 2+ years. Which also lead me to believe that it must be stupid easy to do and I should be able to change it through that sub-domain-appearance menu.
Since I could not change the header on the subdomain without it effecting the entire network I figured I would set-up a test subdomain, not map it and see what happens if I try to change it then. I was able to change it without it changing the header that was on the network (that I only really wanted on the main domain anyways).
So that has brought me to the conclusion that I do not need to map the subdomains. Since (obviously) I am new at this I wanted to verify that I did not need to map my subdomains.
I do not understand why it is hard to answer.
All the directions I found on setting up multisite said to map the subdomains so can you understand why it would be confusing to someone who is new at this?
My set-up is simple. I have 1 install of wp (domain.com) and then have blogs set-up as username.domain.com. I just want to be able to change the header on the blog(s) to the name (or pictures or whatever) of that person.
What I mean by “delete them entirely and set them up again but not map them” was deleting the files and then set them back up with settings, theme, heading and whatever. The reason I said that was b/c its been 19 hours since I deleted the map on the subdomain but they are still showing up as being mapped. I do have wp installed in the root.
Thanks

Bre

A subdomain is not a domain, you do not need to map it.

When you install WP, you get the choice of subdomain or subfolder sites. This is DEFAULT, no plugin needed.

If you want to map a full domain (i.e. example2.com to example2.example.com) that’s different.

Which one are you?

I have subdomain sites. I was confused about the mapping because the directions I followed went right from setting up the multisite to mapping like it was just another part of setting up multisite. I even had my host double check everything I did to make sure it was right (they said it was).
But what I ended up doing was deleting the domain mapping plugin and the subdomain sites (names, folders). Then I re-added the subdomain site and am now able to make changes to it without the other sites being effected ??
Thanks to everyone who tried to help!