You can change your password in your Account Settings page under Account Details.
App:
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 + Mobile browser:
1. Go to Account and click Settings at the top right corner of the screen
2. Scroll down to Account Details and click to expand it
3. Enter your new password twice then click UPDATE.