Changing current font color based on other cell's value?

Hello!

I would like to change the default font color when entering text in Column B based on the text in a different cell. BUT, I would like to retain any differently colored text that has ALREADY been entered in Column B previously. Is this possible?

I am creating a sheet that allows my restaurant managers to enter daily comments about the maintenance of the restaurant. They would like their individual comments to stand out by a unique color assigned to them.

So, for example, if Manager Bob enters "Bob" into the triggering cell, all text written in Column B FROM THAT POINT ON is red, but it doesn't change the previously entered green text that Manager Melissa entered a few hours ago.

Using Excel for Mac 2011

Thank you!