App does not work for me

I spent hours on this app editing on 19 minute video. The app crashed repeatedly, and took forever to upload videos from camera roll. After hours of battling with this app I was finally able to download the finished product....and guess what?? The words don't even match our lips when we talk in the video. They are delayed. Wasted half a day on this all for nothing basically. Also, the playback feature in the app malfunctions as well.