If you want to change the Facebook password, then here are the steps:
Sign into Facebook.
Hit Inverted triangle icon > Settings & privacy > Settings.
Hit “Security & login” in the left sidebar.
Click on the “Edit” button beside the “Change password.”
In the first field, enter your current password. In the remaining fields, enter your new password.
Click on the “Save Changes” button.
Android or iPhone
Open the Facebook app.
Hit three vertical lines > Settings & Privacy.
Tap Settings > Security and Login.
Tap the “Change password” option.
Enter your current password in the “Current password” field. In both the remaining fields, enter your new password.
Hit “Save Changes” button.