Look for a button in the top corner of cPanel: Try the new Meridian theme switches you to the new layout, and Classic cPanel Theme switches you back. Nothing about your account, your files, or your settings changes when you switch. You're changing how cPanel looks and where things are, not what it can do.
Both themes sit on top of the same cPanel account. Switch as many times as you want, whenever you want.
What actually changes
Jupiter (the classic theme) uses the traditional cPanel layout: a left sidebar of icons grouped by category (Files, Databases, Domains, Email, Metrics, Security, Software), and every tool gets its own dedicated page. If you've used cPanel before, this is almost certainly the layout you remember.
Meridian reorganizes the same tools around common tasks instead of categories. Its sidebar reads Dashboard, Websites & Apps, Softaculous Apps Installer, WordPress, Email, Files, Databases, Security, Performance. The Dashboard leads with action-required cards, like a prompt to fix DNS if it isn't resolving, or to fix SSL if a certificate is missing, plus a quick view of disk and bandwidth usage. Websites & Apps consolidates a single domain's settings (SSL, email, DNS, files, backups, aliases, PHP version, HTTPS redirect) into one set of tabs instead of scattering them across separate pages. Meridian also adds a top search bar (Cmd+K), a light/dark toggle, and a floating "Ask AI" assistant.
Neither theme adds or removes a feature. Meridian groups the same underlying tools differently and adds a task-first dashboard on top.
Some tools are classic-only
A handful of tools don't have a Meridian-native page yet and are reached through Meridian's top search or by switching back to classic. That includes Cron Jobs, the full DNS Zone Editor, MultiPHP INI Editor, Softaculous, JetBackup, Git Version Control, SSH Access, and Awstats. If you're used to working directly in one of these and can't find it in Meridian's sidebar, search for it by name first before assuming it's missing.
Which one should you use
If you work mostly in one domain's settings at a time, or you like a dashboard that tells you what needs attention, Meridian is worth trying. If you're used to the classic layout, jump between many tools that live in the sidebar categories, or rely on one of the classic-only tools above, stay on Jupiter or switch back. There's no wrong answer here: it's a display preference, not a data change.
If you're changing a domain's PHP version, the portal's PHP Version tile switches versions per domain regardless of which cPanel theme you're on. Inside cPanel, both themes expose a PHP version control too: Meridian's Websites & Apps > Settings tab, or Select PHP Version / MultiPHP Manager on the classic layout.
If something looks missing
If you switch themes and a tool you rely on seems to have disappeared, it's most likely one of the classic-only tools listed above rather than something removed from your account. Search for it by name in Meridian first. If it's a WordPress child theme's edits going missing, that's a separate issue - see why child theme edits keep disappearing instead. If you still can't find a tool or setting after checking both themes, open a ticket from the portal's Support section. A real person will point you to the right spot or confirm whether it needs to be reached from classic cPanel.