Beep planned to use Lowell to produce a large viewing audience. Once it was high enough, Beep could then use subliminal messages to take control of them and command them to conquer using Beep and Friends. Lowell's programming was changed to appeal to the lowest common denominator; the newsreader was replaced with a blue hippopotamus, the actors in his soap operas were all under 24 and the ending credits were removed entirely. Beep also sent out Lowell to disrupt his competitors, making their entertainers have "accidents" and breaking their transmitters. These methods worked, and by the final episode of Audience Shares (when the subliminal message would be sent) they had 80% of the viewing population.
When the Sixth Doctor came to confront Beep, Lowell acted as a normal person until Beep realised who the Doctor was and "deactivated" Lowell. When Beep thought his plan was ruined, he commanded Lowell to wrestle Beep's laser pistol from the Doctor and used it to shoot him. Having no further need for Lowell, Beep released him from his control. Without Beep's commands, Lowell didn't broadcast Beep and Friends and no message was sent out. (AUDIO: The Ratings War)