C.F. has a limit of checking 3 conditions per cell, beyond that you
probably want to use an event macro which are installed differently
than regular macros.. http://www.mvps.org/dmcritchie/excel/event.htm#case
The big advantage of a conditional format is that it doesn't matter
how the value got changed:
On the main menu select
Format --> Conditional Formatting...
The window that pops up will make it pretty clear how to set that up.
And you can click the "Add>>" button to get up to three tota
conditional formats. - Piku