Regardless if you use the phone app or the security token, please remember to save that emergency removal password. I cannot stressed enough how important that is. Heck, I'll even go as far and say to copy down a physical copy and have a soft copy saved in your computer. And to be on the safe side, copy-paste the emergency removal password directly from the SE webpage. For some reason the last time I had to use it the webpage didn't accept the password I typed manually for some reason. Luckily for me I remembered I had an encrypted soft copy that I pulled directly from the webpage a long time ago.