If you are using desktop website:
After login, click your profile photo at the menu bar on the top and choose "Profile".
Then click the pencil button which next to "Edit details"
If you are using iOS App:After login, click the photo icon on the bottom right
Click "Edit" to edit profile
Then click "Save" to save the information
You can click the basic information to edit it (You can only change once if you want to change name, age, gender)
Click "Save" to save it
If you are unable to save your profile edits, this may be because you are using IE or 360 browsers. Switch to Firefox or Chrome will solve your problem.