Simplicity 3748 HELP!

I need some help with the Simplicity 3748 retro shorts. They came out just awful! They look great until I put them on and then they are a hot mess and a 1/2. This was a "practice" set made from some free material, but I am still upset at how they turned out. I am not sure if I need to extend the seat or what (they kinda ride up, if you know what I mean). The short leg-holes are so wide I could become a flying-squirrel with them! I have made the bolero in this set and adore it, I was hoping for the same result with the shorts. I was wondering if anyone out there has attempted to make these before. Any help would be great.

This is a picture of the pattern: