Select the cell where you want to apply the format rule and click on "Conditional Formatting".
Choose, "Manage Rules".
Makesuretherearenootherrulesthatmightconflict.
Inthisexample,itisempty,sowewillonlycreateanewrule"New Rule ..."
Choosethe"Use a formula to determine which cells to format" option
Inthe"Format values where this formula is true" field, type the following formula
=B7<=TODAY()-15
* Be careful with the keyboard's directional keys as the LEFT and RIGHT keys automatically navigate between cells and enter their respective references in the formula field.
After adding the formula, click the "Format ..." button
Forthistest,let'schangethecolorofthecellonly
Aftersettingtheformatting,clickOK
Onthenextscreen,click"Apply" and "OK"
Themomentyouclick"Apply", the formatting is already applied.
To extend the rule to other cells, just copy and paste.
For cells with existing values, use the "Paste Special" command and choose "Formatting". This will copy only the formatting rule.