It is not a secret that making similar changes to multiple products may be tedious and time-consuming. Therefore, it helps a lot when you can edit multiple products at the same time. In X-Cart, you can do this using the Bulk Editing add-on.
With the "Bulk Editing" add-on installed and enabled in your store, you get a new tool on the product listing page of your store Admin area - "Bulk edit all":
With this tool, you can enable/disable products, put products on sale (or end a sale), and change other product properties (categories, tags, inventory, prices, etc.).