It would be easier for us to help you if you post a sample of your form and code. If you are doing what I think you are doing, and your lists are in a range of cells on a spreadsheet, you can use If/Then statements such as .... 
If ComboBox1.text = "Type" Then ComboBox2.Value = Range("Your range")
. This might be totally incorrect as I don't know exactly what you are working with