because there is no button or gray text to edit my bio. what do I do?

Open https://www.warzone.com/Profile?p=14102297489 in your mobile browser and click at 'Edit your profile'

I still cant edit it because I am not on this account when I go to the website.

1. Go to warzone.com in any browser
2. Sign into your account
3. Click on your username, in the dropdown menu select 'Public Profile'
4. Click 'Edit your profile' (top of the page, in the middle)
5. Edit your bio
6. Save you changes

OPTIONAL:
7. Send a complaint to Fizzer to tell him to update the app so we can edit profiles on there

good idea, but I can't log out of the account that I am automatically on in the website.

well I just found out how to log out.