Time changes automatically with buzzing sou6

This clock uses a Radio Time Server to set its time, that's not to say what's offered is correct as the time zone setting and which time service your click is using may not be correctly set. Make sure the offset from GMT is correct for your location and once set the clock is able to hear the radio signal otherwise it will using its own built in time base.

Things to check is the clock near an outside wall, southward is the best direction in the northern hemisphere. Are the walls brick or metal which can block the signal. If you have a hard time with your cellphone that's a good clue.

The buzzing maybe a messed up Alarm speaker. Here's the product page TFA 602511 Alarm Clock