Do you mean you find a set of records, and you want to set a field to 'Yes', for example, in all of the found set? Like 'Fill down' in Excel?
Then find the set, click into the field you want to fill down, select 'Records --> Replace Field contents...', set the Calculation option to be the data you want, and click 'Replace'.
WARNING: THIS CHANGE CANNOT BE UNDONE! Check carefully that you are:
- in the right field
- setting the right data
- have the correct found set
Thanks, it's easy when you know how!