Sorting Tasks

I used to be able sort tasks by keywords. Once the list was sorted, I could click on a task and close it out. When I reverted back to the task list, it would still be sorted. This would allow to use keywords like 2nd Follow up, 3rd follow up, etc and work on just this list. This is no longer the case. If I sort, once I click a task, when I revert back the list is now unsorted. It is very frustrating.