We cannot see your return ... Rainman deduced the amount from your question.
The tax brackets are graduated ... which means you pay some at the lower rate before you get to the full rate ... see this tool ...
https://smartasset.com/taxes/arizona-tax-calculatorYou need to figure out which rate you want to be withheld at based on your total income ... if you don't withhold enough then you will need to increase that amount or add something to line 1.
AZ form W-4 ... you get to choose your rate of withholding ...
https://www.azdor.gov/Portals/0/ADOR-forms/TY2017/10100/10121_f.pdfAZ tax rates ...
http://swz.salary.com/salarywizard/layouthtmls/swzl_statetaxrate_az.htmlAZ withholding rates ...
https://www.azdor.gov/Business/WithholdingTax.aspx
