Your camera password is saved in the camera. The HiKam app also has a camera password. Don't get confused. These two passwords play different roles, and they work together to ensure only legislate user can access.
Let's use a real world practice for illustration. You register an gmail account and a password. The credential pair (account and password) are stored in Google server.
When you try to access your account, you open the web browser and type in your account and password.
In our case, the camera ID and camera password saved in the camera is just like your gmail account and password saved in Google server, while the camera ID displayed on HiKam app and the password displayed when tapping Settings > Modify DeviceInfo is like the information you type in the web browser.
To change the password saved in the camera, tap Settings > Device Password.
To change the password on the local app, tap Settings > Modify DeviceInfo.