Rtk is float instead of fix

my rtk here+ is float instead rtk fixed.
how to i change that?

are you outdoors? it doesnt work indoors. you need to wait until it gets a better fix before it switches to RTK lock it can take some time, If it never goes to fixed then you need to look at sources of interference onboard the aircraft, some LIDAR modules are bad for gps interference, some cameras are bad for it. unplug everything non essential to see if it helps.