Windows 11 keeps changing by itself the user accounts in shared foldes in local network

Hi, everyone! Like many of you, I have been struggling with 24H2 when sharing files.
I have a weird (even for Windows network standards) problem. I decided to restrict some folders to some people, so I turned the password-protected function on for the first time in my life. I knew it would be a mess (I struggle with network issues since Windwos Me).
I need to share some folders with some people, and others with other people.
I managed to create the local accounts, turned on the "share only with password protected accounts", and use both tabs to share, normal tab, and advanced tab*.
After a day (without rebooting, I never turn off my computer, this is an office), they users with whom I shared a folder in the Advanced tab disappear, and the user EVERYONE appears. I change it again, I remove EVERYONE and add the users I want. The following day, the same story. So, now, every workmate depends on me to access the files every morning, because, to add more weirdness, sharing with EVERYONE sometimes breaks the access, instead of opening it wide to all. I attach a screenshot of how it is now and it should always be (earlier today it was shared with EVERYONE again).
I reset networks parameters, but nothing changed.
Does someone one has an idea? I spent hours in this. Thank you, EVERYONE!




*Even Microsoft support help does not know why there are two tabs, and why they do conflict so often. It simply says "they are meant for different purposes", without clarifying which purposes they are.

This is an English speaking forum. All your screenshots are in a foreign language so I can't read them.

As messed up as sharing can get, and in some cases already is in windows, I wouldn't touch that arrangement with a 10 foot pole. However,
try creating a Windows credential for an account & password on both client and server computers you are sharing files between.

Control Panel>credentials>windows credentials>add a windows credential

You can also consider using cloud storage, sharing certain folders with certain people.

Thanks for the reply. Yes, I know, but I can't translate the images to English. They are commonplace for those who has used sharing, though.
I did that with the credentials before posting, it solved the problem in some computers, while not in others.