If you registered your user account with an email address: Go to your profile by tapping on "You" at the bottom right of the app.
Then select "Personal profile".
There you will find the option "Password".
Start by entering your current password. Then enter your new password. Then enter your new password again. Once you have clicked "Save", you will receive confirmation that the new password has been saved.
Please note that you cannot change your password if you have created your user account via Google or Apple.