Excel Functions/Formulas

Here’s what I am treating to accomplish for a spreadsheet for bills:

On column F there’s bill amounts in each row, example:

F3=$674

F4=$24

F5=$329

On column G, I add the word PAID once the bill has been paid.

Now, on row F17 I have the TOTAL of all cells in the F column. 

I would like to whenever I add the word “PAID” to a row, for the total amount on F17 to subtract that PAID row ONLY and give me an updated total amount. 

I’ve been able to come up with 

=IF(G3="PAID", F17-F3, F17)

but this is only working for the G3 cell when I enter the word PAID and I can’t seem to make it do it to the whole column! 

hope this makes sense.

thank you in advance!