You can just set it in your slicer software such as cura, it should be under cooling in cura, and any other software.
but if im honest these printers with the current fan setup, you almost need that 100% fan speed when you are printing. There's mods you can do to add more fans and run them slower.
such as this
But I do know a lot of people have complained about the stock fans, I mean its a cheap printer, so they definitely were not gonna invest in quite fans.
So that's my advice, I personally run mine at 100% but you do what works best for you, especially if the fan noise is a deal breaker.
If something I said just helped you out tremendously you can drop a little ramen money, the coding monkeys in my basement will appreciate it -
Feed them here
You can private message me if you have any questions I might be able to help.