You can change your password in your Account Settings page under Account Details.
App + Mobile browser::
1. Click on the Profile icon at the bottom
2. Select Account Settings
3. Scroll down and click Account Details to expand it
4. Enter your new password twice then click UPDATE
Desktop:
1. Click your name on the top right of your screen, then click Settings
2. Scroll down to Account Details and click to expand it
3. Enter your new password twice then click UPDATE.