Excel Table Autofill using IF() Statement

I'm trying to build a table in Excel that uses IF() statements to apply different formulas to the same cell based on characteristics in a cell at the top of the page, but running into issues as the columns that contain the IF() formulas don't autofill correctly.

Example: We have certain billable rates that are pulled from a VLOOKUP based on input from an adjacent column, but if an individual wants to override that billable rate with a flat rate or a broadly applied % discount they enter at the top of the worksheet. I'd like the formula to update to reflect the new numbers, but also autofill when the individual adds a new row. Thanks for the help!