I am trying to create a formula which counts the number of accounts where a particular condition is met but the output is instead counting opportunities relating to those accounts 

The formula I have is "countif("Accounts"."ATS Contract Go Live Date"<(currentdate()-90))"

I want the number of accounts which are over 90 days old but the above formula keeps counting the total number of opportunities relating to these accounts which obviously gives a higher figure than it should 

Thanks

Sarah