There are a couple issues with Time reporting on JIRA that are becoming very irritating and for what this community pays in subscriptions; there is no reason this should not be resolved. Known Issues that need to be corrected:
The desired behavior would be that subtask estimates roll up to the story (which is does today). When one logs time it calculates the remaining time correctly at the subtask level and that rolls up to the story and the stories roll up to the Epic. Then when one records their time on the subtask and that time exceeds the estimate, the time remaining goes to 0. It would also be good if in the story, time remaining was displayed next to each task so you did not have to go into the subtask to see the time remaining.
Scroll right on the image to see the area of concern.