Each column can be sorted ascending order or descending. Simply click on the column header to change the sort order by that metric.
Columns can be added or removed from the "View" menu or the table customize button.
To arrange securities in your watchlists manually by dragging and dropping rows above or below one another, you'll first have to turn on "Manual Sorting". Once Manual Sorting is enabled, you can drag a watchlist row (e.g. Apple Inc. AAPL etc.) to its desired location in the watchlist. Clicking on a table header will cancel Manual Sort mode and take the app back to Auto Sorting.