You need to plug it in with the USB to the computer firstly and then you can visit this website http://app.runcam.com/tool/ for updating.
You can check it firstly. If it's the latest firmware, you can set and save the setting directly.
If not, you should download the file RUNCAMHD.BIN to your SD card(note: don't put it in any folder and make sure the name is RUNCAMHD.BIN)
Then when you turn on the camera, the indictor B will be red, firstly it will flash slowly then qucikly. When it finished, it will turn off automatically.
You will find that the file on the SD card will be DUMPCFGINFO.bin. It means that you updated successfully.
And you can choose load this file and set the camera to your preference.
Here is a video for you to know more about the steps: