My Template

[denis]

If I make any changes in My Template Plugin config they do not save. I am using GS site in a sub directory, could that be a problem?

Perhaps, because of this, the settings are not saved in the right place. Maybe file permissions may not be set.
But I installed the standard CMS without any configuration changes. There were no such problems.

Demo site on subdomain and subdirectory.
But I had to make changes to .htaccess in the root directory. But this applies only to my case, because I use free hosting. On my hosting, the subdomain can only be directed to the root directory.
RewriteEngine on
RewriteCond %{ENV:REDIRECT_VHOST} ^$
RewriteCond %{HTTP_HOST} ^(www\.)?(.+)\.p9021271\.beget\.tech$
RewriteRule ^(.*) %2/$1 [L,E=VHOST:1]
I dont think it will help you.

The configuration is written as follows: '../plugins/my-template/cfg.php'
Edit: /plugins/my-template.php & /theme/template.php -> 
Comment out the line: Error_Reporting(E_ALL & ~E_NOTICE);  It is almost at the beginning of the code.
See if there are any errors.

There were no problems on the local server and in the root directory. And on subdomains on the local server everything also works.