[Adrian Sanchez]

I just had this problem. I had cut a sequence together and it was the wrong resolution for some reason. so instead of making a new sequence with the desired settings and copy and pasting, i just pressed command+0 and changed my sequence settings. then i selected all my clips in my sequence and went to Modify>Conform to Sequence.

if you have a few clips in your timeline that match the sequence settings it will prevent you from being able to select Conform to Sequence. deselect those clips and choose it again.