bernie (and this may vary for different expedia sites), but on expedia.ca you go first to advanced flight options (at expedia's opening screen undernath the city pairs on express search), then choose Lowest Fares. Unfortunately, you will not get all the fares for many routes if you select "all airlines" so narrow it to one airline if that happens. There seems to be a maximum, non-adjustable limit on the number of fares that Expedia will list (or flights on other parts of the booking engine) and you cannot choose "more" like you can on Travelocity.

I don't know why expedia doesn't have a "more" fares option at the bottom of each results page. I have complained about this for a couple of years. They have increased the number that are listed, but still will not list them all.