http://yongnuo.com.cn/usermanual/pdf/YN568EX_EN_USER_MANUAL.pdf

14-15. oldal, 6.-os pontban: 6.

Sc/Sn and S1/S2 Mode Set the speedlite to be Sc by pressing the [MODE] for a long time, and then operate [MODE] button, and the speedlite shall switch between Sc/Sn/S1/S2, and these four modes all shall be applied as off-camera dependent unit