Is there a way to replace drum kit on beat designer for personalized sounds?
Since Beat Designer is a MIDI Insert it will play whatever sounds are on its Instrument Track. If you put it on a Track with a Piano VSTi it will play piano not drum sounds. If you stick it on a Track with Groove Agent SE you can assign sounds there and have it play them.
in which page I can see that information? as I didn’t see it
Not sure what you are referring to by this