How do you change your Facebook page's profile picture? (On an android)?

Open your Facebook app.

Go to your page. You can access it by clicking the 3 horizontal lines on the right side of the screen and choosing the name of your page from the list.

It will lead you to your page. Click your profile picture. Something will pop up that says "upload photo" and "view photo. Choose the first one.

Choose the pic you want from your phone's library.

note: you must be an admin of the page to change it.