On legacy plans (Studio, Firm, Enterprise, Spec Lite, Spec Pro), you can add statuses unique to your workflow.
Note: On Core and Core Plus, every account shares one set of statuses, so custom statuses aren't available in new projects. To track your own workflow, use Product Tags instead. See Product Tags: Create and Manage Them.
Step 1: On the left side of your account, hover over the profile icon in the bottom corner. From the menu, select "Settings."
Step 2: Select the "Statuses" tab.
Step 3: There are a total of 25 statuses. Gather starts you out with 9 default statuses. 3 of these, shown below, cannot be edited or deleted as they are tied to the client side of the system.
Step 4: The remaining default statuses can be renamed by clicking on the pencil icon or deleted by clicking the trash icon.
Step 5: To add more custom statuses, simply click "Add Statuses" and enter a name.
Step 6: Statuses can be reordered by clicking on the 2 lines and dragging the status up or down into position.
To learn more about Custom Statuses, check out this video