My scale does not weigh accurately. How do I fix this? A 35 lb weight comes up 33 lbs on the scale

Cheap scales do that,

some better scales of an autocalibration, mode, RTM
read the manual, google for it using its real name and model #
then read that see if it has that feature,
a 6% error, if the manual tells you scale is 5% accuracy that be normal. no scale told of 10,000 models sold world wide.

Make sure the scale is zeroed before using, then weigh an item 3 times and take the average weight.