why are you disarranging our sub forums? and rearranging them to other forums and even removing sub forums and making them entirely a forum of their own without subforums??
why do you do that?
We do nothing on your forum. The only admin is you. So my question is; how are you disarranging your sub forums? And why you're asking this question us?
Please be informative, we can't follow you. Leave some screenshot and explain your issue.
We don't ask for support. We help our users for free as much as we can.
First please try this, but change the value from 4000 in examples to 10000:
https://themezly.com/docs/how-to-increase-the-max-input-vars-limit/
Directive for .htaccess
php_value max_input_vars 10000
php_value post_max_size 512M
Directive for php.ini or .user.ini
max_input_vars =10000
post_max_size =512M
Directive for wp-config.php
@ini_set( 'max_input_vars' , 10000 );
@ini_set( 'post_max_size' , '512M');
Once you changed, go to Forums > Forums admin page, change one forum to sub-forum and save it. If it's saved then the problem is fixed.