kassie wrote:
Select range A20:M20. Click on Format, Conditional Formatting. Change Cell
Value is to Formula is, and insert =$M$20=1. Click on format, select
Patterns, and select the colour of your choice.

This works, but only if I type a new value in M20, not when a value exists.

When I paste new data into columns A:J, this affects the formatting as well.

Could this be done for all cells in M?

=$M$1:500=1??