YongNuo YN-468 II Speedlite.

I recently purchased one of these speedlites to go along with my canon 420EX and 580 EX II units.  So far the YN-468 seems to be a fairly good purchase for the money.  I'm currently using YongNuo 622c triggers to fire all three speedlites.  This works well in manual and ETTL modes.  But I was also interested to see if I could use my canon 7d's remote ability to fire the YN-468 flash.  Should be simple.  Put the YN-468 in slave mode and have at it.  But when put in slave mode the output is set to 1/128 power and I cannot find anyway to change this.  The manual is slim and gives no clues.
Any one here used the YN-648 or any of the other YongNuo speedlites?  If so have you hit this same snag or know how to work around the problem?
Thanks
Andy