I am making a couple of assumptions:
- I assume that by “I have a category called feature that displays the
latest post” you mean that you are displaying the latest posts in
your “featured” category - I assume that your “featured” categories have their own template
which has a query that displays them.
Assuming those assumptions to be correct, you need to alter the query that pulls your featured categories so that it sorts by post_modified instead of post_date. If you will post your query I will show you how to do that.