I am trying to read and output values from certain sheets. whenever I use the analytic app to allow the user to choose the files, the value is never updated and it always ends up using the default file set in the input and output tools.
Does the file that your users choose have the same sheet names your default file does? e.g., Sheet1
Can you share your app workflow?
I had the same problem when I started to use interface tools. It will be helpful if we can see the workflow or just upload some screen shots of the interface tools. I don't think you need to add any interface tools to the output tool.
If you can upload your workflow, it will be easy to pin point the issue.
Can you confirm that you are running via the wand?
If so - check your action tools to see how they configured. This often happens because you've packaged your workflow and then unpacked it. During this process Alteryx has changed your original location with a new relative path like ./externals/... - if your original action tool was configured to look for a static path - it now can't find it. The action tool looks to replace a path which does not exsist in the string - and nothing changes.