LG 26LC2R - How can I activate Sound in PIP?

Hi, I have recently adquired this model of LCD TV, And before I had a Samsung LE27S71.

I Used to use PIP a lot & I'll Like to know how to activate the sound in my LG TV, I've seen the manual, but I haven't seen anything about this.

How can I activate Sound in PIP?

Thanks.

Any suggerence? thx!

May I make an ''up'' for my doubt?

up?