I don't know if you can turn off the one-finger chord recognition on the PSR-E433, but all you need to do is play the chords with as many fingers (notes) as you want. There used to be a page that listed all of the recognized chords in the Owner's Manual of the older models (such as the PSR-E403), but it's no longer included in the Owner's Manual of the newer models (such as the PSR-E433). However, I was recently informed that Yamaha moved that page into the Song Book for the newer models, so download the Song Book for the PSR-E433 and see if that page is there. Note that I don't mean the chart that shows something like four chords for each key of the diatonic scale, but one that lists about 35 or so different chords for the key of C. That list gives the notes you need to press for each type of chord, and indicates which notes are optional and can be omitted.