As discussed before, you can do two tests.
Test 1: Save your parental control settings. Log out and log back in. Check the parental control settings. Do they remain intact?
Test 2: If the settings did not change in the above test, reboot the router. Log in and check the settings again. Do they remain intact?
If for both tests the settings remain unchanged, but the settings are changing by themselves again, then most likely someone is going in there to manually change the settings.
To reduce the number of ways the settings can be changed and identify the root cause:
1. Disable remote control: in Cloud Settings, uncheck “Enable Remote Management” and save.
2. In System Settings, under the Administration section, click “Change Router Password” to change the router management password.
You should do the above two steps from a device that is used exclusively by you, and access the router management pages via HTTPS. I.e., use https://pcwrt/, or https://192.168.10.1/. You’ll get a warning when you first load the page, just ignore the warning and move ahead.
After you do the above, log in periodically to check the settings. Again, only from a device that is used exclusively by you, and via HTTPS.