This is assuming you have run the laser wizard and not using your own custom built pipelines.
First, make sure time calculations are correct
The laser wizard set of pipelines first calculates the time to cut, engrave, and score. So in order get get accurate prices, those need to be accurate.
Go into Constants to change the price-affecting constants.
Constant: Laser hourly rate
This is the hourly rate you charge for every hour the machine is running.
Constant: Laser minimum unit price
This sets the minimum price for an individual manufactured piece. You can also set it to 0, if you want no minimum price. But it's always a good idea to have some minimum, due to part handling etc.
Constant: Laser minimum total price
This sets the minimum price for the units times the quantity. Everything sum that is below this is replaced with this price instead.