Qwic PRD9 Manual page 59

Shimano Deore / Alivio with 9 gears
The Shimano Deore / Alivio is a derailleur gear with 9
gears.
It can be manually controlled with the two shifters next
to the right handlebar. The lowest one (controlled with
the thumb) shifts 1 gear up/lighter with a small push
or 2 gears up/lighter with a big push. The upper shifter
(controlled with forefinger) shifts 1 gear down/heavier
with every push.
It is important you always keep cycling when you shift
gears, but don't use force on the pedals while shifting.
Never shift gears when in a standstill. The display of the
shifter shows which gear you are in.
Fine tuning derailleur gears
To avoid unnecessary wear and noise from the chain,
you can make sure that the derailleur wheel is in a
straight line with the cassette wheel. The chain should
also run in a straight line. It is possible to fine-tune this
at the rear derailleur or with the adjustment screw at
the shifter.
General parts of the electric bicycle 59