Article updated for v2.0.7.
You can reorder your apps or workspaces in the tab bar by dragging & dropping them. The new order will be synchronized between your devices.
Take into account that, in order to prevent accidental sorting, there is a slight delay before you can move and reorder your apps and workspaces. Therefore, you'll have to hold the item pressed a bit before the drag and drop takes place.
If you are following these steps and the drag & drop function doesn't work, please, try doing a Clear Cache and restarting Rambox.