the UST is slow; is that in purpose?

yeahs, I've downloaded some USTs and made the voicebanks sand them. but when I tried to mix the exported UST (which means in wav) with the off vocal song, the UST is too slow and if I make it faster, the voice would be a little different.

it already happened more than twice, and the maker of the USTs are different. is that in purpose? if so, could someone tell me what should I do to make the UST plays in the right time?

well, I hope it's not really difficult since I'm really new to UTAU. I don't even know what's flag and Mode2 used for
thanks in advance :>

Umm...
You would ACTP it.
Or set the tempo.

eh? what's ACTP? ^.^"a
and how to set the tempo?