How do I change the default app association for a specific file type

[Windows Central Question]

Hi!
Got my first Windows Phone today....and ran into troubles.
I wanted to open a .txt document what doesn't seem to be supported natively. So I browsed for an App and installed it.
Well.. wrong app.. didn't work so I browsed for a new app that suites much better.
Now I have the problem hat Windows Mobile 10 seems to have registered the first app I downloaded as default app for the file type (.txt).
How the heck do I change this?
Uninstalling works. But.. hey.. that can't be the solution.
So the question is: Where do I edit the file associations in Windows 10 Mobile?

Many thanks in advance.

 

[TechFreak1]

Download the office mobile apps .

support.office.com/en-gb/article/Install-Office-Mobile-apps-on-a-Windows-10-device-2b7c1b51-a717-45d6-90c9-ee1c1c5ee0b7