Korg pa50 SD ... Help appreciated on STS..

[LouLou]

Help appreciated if you can share your experience / expertise on Pa50SD, I'm a novice in keyboard. With F1,F2,F3,F4 buttons under Single Touch, I hope to save various instrument voices into STS1,STS2,STS3,STS4 under any style & recall them by the 4 single touch buttons. I found it can only do so on one STS only because it will default to factory setting as soon as I start switching to another STS. I tried turning off factory protection through utility under the SD card button with no success. I hope it's procedural error on my part. To me, it should be easily arranged. Please help.