If you want to update the filters included in an existing view, enter the view you wish to edit and click the + button next to the existing filters.
Select the filters you want to add to the view. Click Update View in the upper right corner to open the view editor.
Here you can edit the view's name, URL, and filters.
The new filter you added will show up next to the existing filters.
Click Update to apply your edits.
Any new filters will now be applied when you access it from the sidebar.