To change PHP for an entire domain, use the PHP Version tile on your service page: Services → your hosting → PHP Version, pick the domain, choose a version from 7.4 to 8.3, save. That's the per-domain switch most people need.
If you need a different version for one specific folder, that's not what the PHP Version tile does. You want cPanel's MultiPHP Manager instead, which lets you assign PHP per domain and per subdomain independently, including overriding just one addon domain or subdomain while the rest of the account stays on its default.
Whole-domain switch: the PHP Version tile
From your service detail page, open the PHP Version tile. It lists every domain and subdomain on the account with its current PHP version next to it. Pick the domain, select the new version, and save. This takes effect immediately, no restart needed.
Our system default is PHP 8.2. Most WordPress installs and modern PHP apps run fine on 8.1-8.3. Only drop to 7.4 or 8.0 if you're running old code that explicitly breaks on newer PHP, and treat that as temporary. If you're not sure what a specific WordPress plugin or theme needs, check its documented minimum first rather than guessing.
Per-folder or per-subdomain: MultiPHP Manager
Open cPanel (one-click login from your service page) and go to Software → MultiPHP Manager. This tool shows every domain and subdomain as separate rows, each with its own PHP version dropdown. Select the ones you want to change, pick a version from the dropdown, and click Apply.
This is the tool to reach for when one subdomain runs an app that needs PHP 7.4 while your main domain runs a current WordPress build on 8.2. The two don't have to match.
Extensions are toggled separately in Select PHP Version (the CloudLinux PHP Selector) in cPanel, where you can enable individual extensions like imagick, redis, opcache, or intl per domain. If an app throws a "missing extension" error after a version change, check there before assuming something's broken.
What the PHP Version tile does not do
It only switches the version number. It has no effect on PHP limits like upload_max_filesize, memory_limit, max_execution_time, or post_max_size. Those live in a separate tool: cPanel → Software → MultiPHP INI Editor. Pick Basic mode for the common limits with a simple form, or Editor mode to paste raw php.ini directives for a specific home directory or docroot.
So if a plugin update needs PHP 8.1 and a bigger upload limit, that's two separate changes in two separate tools, not one setting.
After you switch
Reload the site and check for fatal errors right away, especially on WordPress. A theme or plugin built for an older PHP version can throw fatal errors on a newer one, and vice versa for very old code on a version that dropped support for deprecated syntax. If something breaks, you can switch back to the previous version in the same tile while you sort out the compatibility issue with the plugin or theme author.
For WordPress specifically, run a quick pass through Plugins and Appearance → Themes in wp-admin after any version change, since that's where PHP incompatibilities usually surface first.
When to contact support
If a version change causes errors you can't trace to a specific plugin or theme, or MultiPHP Manager isn't showing a domain you expect to see, open a ticket from the portal (Support) or use live chat. A real person can check server-side logs for the exact error behind a blank page or 500 error.