How to select an App to open a file in Files App?

It's not clear how Files App determines which App to use to open a file. From our observation, it may use the App which opened the same type of files in the last time. To be able to select a preferred App to open a file in Files App, please follow the steps below:

1. In Files App, find the file you want to open. Long touch on the row of the file to bring up the context menu. (Please note, if you long press on the row of the file, a preview window will be shown instead). 

2. Select "Share" and then choose "Copy in ...", in which "..." is the preferred App.

The file will be opened in the selected App.