The "Filter Stories" bar can be used as a search tool to surface specific Stories in the Epic, and the individual Epics page also includes sections for discussion and reporting. Applying other Filters can help you view just a small subset of Stories.
You can also change the view of how you'll see your data by clicking the headings of each column above the Stories Table view. If you choose to sort by Priority in the Table view, you'll be able to drag and drop Stories to denote priority. When you drag and drop these Stories, the priority order will also be changed on the Stories Page view of the Epic. Please note: you'll need to be sure that the Priority arrow is toggled to the down position (see below) so that the priority rank view matches the Stories page (in each case here, the highest priority Story is at the top of the list).
If you'd like to manipulate this date further, you can export a CSV of all of the Stories in an Epic by using the Export button.