Home office: Enter real estate property taxes page issue - itemized or not

I'm on Business/Home Office/Enter real estate taxes: It says "if you paid real estate taxes but are not itemizing deductions, do not enter here, enter as excess real estate taxes later". HOWEVER I DON'T KNOW IF I AM ITEMIZING OR NOT YET! YOU - the PROGRAM - determines that later! So how am I suppose to decide? ALSO: I entered $2000 here in December when I was estimating where i was ... I now changed that to 0 and entered the right amount under Excess Real Estate taxes... $1940. BUT later under Personal for my home it says $1641 and when I hit UPDATE (grayed out) it is STILL showing $2000 for real estate taxes paid!!!!! I CAN'T change it!!!!! I'M STUCK and its 4/12!!!