An apparatus for controlling synchronization of on-screen display information in an auto-search mode of a radio-frequency receiver (2) connected to scan an incoming signal for valid channel frequencies, includes a picture intermediate frequency phase-locked loop detector (17) for supplying an output signal indicating whether an intermediate frequency demodulator is in an unlocked mode which is the case if the incoming signal frequency does not correspond to a valid channel frequency, or in a locked mode, which is the case if the incoming signal frequency does correspond to a valid channel frequency, a video detector (18) for detecting a video property in the incoming signal, a synchronization phase control loop (6, 8, 10) which is closed if the video property is detected and the output signal indicates the locked mode, a memory for storing the frequency of the incoming signal as a valid channel when the phase control loop (6, 8, 10) is closed, and a horizontal oscillator (8) connected to free run when the phase control loop (6, 8, 10) is open. This stabilizes an on-screen display even when no signal is present or a weak signal is present.