Humidity Control Project w/ Desiccants

To start, I am brand new to arduino, so I apologize if this question comes off as trivial. ALso thank you in advance for any advice.

I have been assigned a project meant to control the humidity of a small closed system for a biology lab. As of now the plan is to use a container of silica beads, which will be open and closed with a servo motor controlled by an UNO. I would like to be able to set different humidity targets without adjusting the code each time, a different experiment is done. So my question is:

Is there a mechanical toggle system I can use to mechanically set target humidity without adjusting code manually every time I want to change it? I only need 4 settings.

Just use a push button that will sequence through the 4 settings.
If it has to be sealed inside the box you can use a magnetic reed switch.

Or, go full Monty and have it hook up to an external PC, you can set any humidity you want and get a readout, too. Just be careful, careless use of the serial port can reset the processor.