1. Open the tab that contains the setting (e.g. Theme > Kitchen).
2. Click the value in the Value column (empty values show Click to set; hovering shows a pencil icon).
3. Type the new text, pick from the dropdown, or tick the checkboxes for multi-select settings.
4. Click the orange check mark to save, or the X to cancel.

The change is saved immediately to the database and written to the activity/audit log; there is no page-level Save button. Dropdowns with more than a few options include a search box.