FTP access rights for the user

I am trying to change files via ftp as a user.

But I am getting access denied when saving the file.
I created an additional ftp through the user’s domain.
I have no problem logging into my FTP account.
But I can’t change the file via ftp.
I tried to change access by user’s SSH bash and others.
I tried to include in the domain custom document root.

But I couldn’t get the result.

Can this be solved somehow?

Check what the file permissions are

File Permissions 644
But I can make these changes via admin
And I can’t change file permissions as ftp user.
I need the administrator to change file permissions for the user.
And after the changes returned them back.
For security.

The question is quite simple in the end.
How can a user work on ftp within access to his files without restrictions?
Otherwise, the user will not be able to work normally via FTP at all.

If the user cannot change the permissions of his files, and therefore cannot edit them, then what can he do with his files?

if a user dont have permission to edit his files, he should not be able to change that at all. Check the file ownership, probaly root:root instead user:user?

Where can I check it?

should be basic knowledge: login as root, cd to the user dir, run a ls -la and check ownership - if wrong, correct with chown. Please run man command (man chown) before you run them.

I understand it.
I mean the ability to set permissions for the user in the panel. I understand that it is impossible to give the user full rights to his site through the panel?

I once worked with the Vesta CP panel, this issue was resolved there.