In case you'd like to change the PHP version for a specific subdomain or subfolder, all you need to do is:
Open your .htaccess file
First, access your File Manager:
Then, access the folder to which you would like to apply a different PHP version. If you want to edit a subdomain, access its folder. In this folder, open the .htaccess file by double-clicking on it.
If the file doesn't exist, you can create it directly in the File Manager. Make sure to include a dot (.) at the beginning of the filename!