Hey.

Todays the big day that overdrive has the new update.  If you are using a phone app just go to where you normally do updates and make sure it's updated or click on it to update.

Then  you can sign into Overdrive one and sync up between your ipad, kindle fire and phone so you can switch to one or other with the same book
To access the Overdrive one, just swipe LEFT when on the bookshelf screen, and it will be listed as one of the options.