continental yarnover

[bonniejean2]

I am a beginner knitter and I do continental (taught by my mom). I have a pattern that uses a double yarnover. So I viewed the video and had no problem. But when I went to the purl side, the yo part kind of unraveled and looked bad from the right side. So a friend of mine suggested wrapping the yarn over the needle the opposite way that I usually do and it came out looking good (nice little hole) with no unraveling on the purl side. I hope I'm explaining this alright.

Can someone tell me why this happened?