A communications apparatus includes a wireless communications module and a controller. The wireless communications module uses a preferred receiving beam determined in a beam training procedure to communicate with a network control device and further monitors one or more candidate receiving beam(s) by using the one or more candidate receiving beam(s) to receive signals from the network control device. The controller calculates a detection metric for the preferred receiving beam and the preferred control beam and a detection metric for each combination of the one or more candidate receiving beam(s) and the preferred control beam, and determines whether to change the preferred receiving beam according to the detection metrics for the preferred receiving beam and the preferred control beam and for each combination of the one or more candidate receiving beam(s) and the preferred control beam.