hi. i'm not a FCP expert, as i'm still getting used to it myself.
Usually, my newbie workaround is to open a brand new sequence, then to drag my HV20 clips into that timeline. That usually produces a pop-up that asks me if i want to change the timeline to conform to the clips, and i just accept the change.
Another way i've done it i think is to use the FCP browser in the upper left, expand that window so that all the sequence and clip settings are spread out by column. From there, you can just glance between the rows to see the setting differences between your clips and the sequence (frame rate, aspect ratio, etc). You can then right click the sequence and pull up its settings and change it manually to match the clips.
again, this is my non-pro newb solution. Hopefully one of the FCP jedi's chimes in. But in case they don't, maybe this will work for you.
