To change your name on Facebook using the Facebook app on your iPhone, you can follow these steps:
1. Open the Facebook app on your iPhone.
2. Tap on the menu icon (three horizontal lines) located in the bottom-right corner of the screen. This will open the menu.
3. Scroll down and tap on "Settings & Privacy."
4. In the expanded menu, tap on "Settings."
5. Scroll down and tap on "Personal Information."
6. Tap on "Name."
7. You'll be prompted to enter your password for security purposes. Enter your password and tap "Continue."
8. On the "Name" screen, you can edit your first name, middle name (if applicable), and last name. Tap on the field you want to edit and make the desired changes.
9. After making the changes, tap on "Review Change."
10. Review the changes you've made to your name. Facebook may provide some guidelines or restrictions for changing your name. If everything looks good, tap on "Save Changes."
11. You may be asked to confirm the name change. If prompted, tap on "Continue."
12. Your name on Facebook will be updated to the new one you've chosen.
Please note that Facebook has certain policies and restrictions regarding name changes. Make sure to follow their guidelines when changing your name to avoid any issues or account restrictions.