Yes you can easily change this!
Switch the indicator to the right for 1 flash, then switch to the left for 2 flashes, then switch to the left again for 3 flashes.
Then keep switching like this between left and right. You'll hear all the different sounds.
When you hear the sound you want you can push in the switch indicator and the selected sound will be set.
The volume of the blinker sound cannot be adjusted.