Account preferences apply to your user, not to a single storefront project. Open them from the sidebar under Account → Preferences (labels match your Cockpit language).
The Language section lets you choose the Cockpit UI locale. After you change it, menus, dialogs, and built-in copy use the selected language where translations exist.
Under Profile information you can update your personal details (such as first and last name) shown across the product. Save changes according to the form actions on the page.
The Color mode / Theme controls how the Cockpit shell is rendered:
Pick the mode that matches your accessibility or workspace preference. The setting is stored for your account session/device as implemented in the product.
The same account area may show internal account identifiers or fields that cannot be edited in the UI; those are for support and troubleshooting only.