The screws look the same as mine.
If you PM me your email address I will try and send you what instructions that come on the thumb drive with the printer. Or email Qidi email address on the side of the printer for the operating instructions.

There seems to be a lot of powder dust round the extruder, I had this when using PLA with the hardened nozzle in the high temp extruder, possible that hardened nozzles are not good for PLA.

To remove extruder.... Remove the thumb screws top and sides, turn power off and unplug the ribbon cable from the extruder. The thumb screws actually only engage a few threads at the end.
Undo the three screws on top of the extruder and behind the gantry rail and the four screws on top at the front, the extruder will drop into your hand.