I have been using Keepass on my Win7 desktop for a few months. I decided to download the app to my phone. When I try to open the files with Android, it won't open and a "very fast" message pops up saying something about converting my database to new file format and I can't find any instructions on how to do that.
You didn't mention which version of KeePass you are using in Win7.
If it is 1.x, then your database uses the .kdb file format, while version 2.x uses the .kdbx format. They are not interchangeable - but there are ways to convert the format from one to the other.
Check that the Android client you are using is compatible with the file format you are using in Win7 - assuming you are using the same database for both.
I use KeePass2Android and it's fine with my V2 database.