In the window for the personality, under the 'signaling' tab, you'll find the signaling squelch drop-down box. "AND" means the radio will listen for the correct PL tone, and the correct QC tone before unmuting the speaker. "OR" means it will unmute for the correct PL or the correct QC tone.
Basically, on "AND" it will stay quiet until the tones come across, and on "OR" you can still monitor the channel.