my app is MOVIE CREATOR BETA. microsofts own..Is it this app? PowerDirector Mobile Video Editor – Bundled – Windows Apps on Microsoft Store
If that is the app - it looks like you need to activate it to be able to export to a higher resolution. I'm not sure what the activation cost is for this particular app. check if there is an activation link and click on that to check what the pricing is.
Thanks for the link.. I have found out that I movie on my iPad mini uploads to YouTube in HD.Meybe this will help you:Nice video though!