Im a newbie and im trying to make a rubber stamp however my power settings are not the same as every tutorial ive watched.
My power only goes to 10 (and i need to set it to 90)
and my lines per inch need to be setup to 450 and it only offers 405.
I also have to select vary power which is not offered to me.
If your power goes to 10, I believe you have either the Aura or the Spark. Both of those machines have lpi settings that go higher than 405, but it is unlikely you will need anything higher.
Kindly share a screenshot showing your material, and the side of the interface showing your speed settings.
You are watching videos of the Glowforge performance printer which is a C02 laser. The Aura is a diode laser with settings that are completely different. There is no simple formula for converting settings from one machine to the other.
Here is a post that may be helpful to you. Whenever using non Proofgrade material, you need to test until you dial in settings that work for you.
As for the vary power option, that is only an option for certain file types. I think you need rasters for vary power engraves rather than vector engraves. If that is incorrect, someone will chime in with accurate info.