IF then or else leave alone VBA

[Cori_W]

I'm trying to create a VBA or worksheet change event so that when the client turns 6 the YOQ column turns to todays date, if the client is under 6 the YOQ column would return Under 6, and otherwise leave the cell unchanged
I want the same thing to happen for the CYOQ column, except when the client turns 12. Does anyone have experience in this? I was thinking an If then or else leave unchanged kind of VBA but I don't know what kind of terminology to use. I attached an image of a sample worksheet

excel.jpg