sup guys

a little about me. im a truckdriver and i needed a spreadsheet to keep track of miles,fuel expense and quarterly. i found one and copying it for personel use. not exactly for those who just say buy it i like to make my own. the problem im having is i have a dropdown menu thats has all 12 months i also have it set up for the quarter but i cant get it to reset to 0 when i change the months, and put in right month for the quarter