Using Windows 10, how do you change the timeline time scale on a saved file that you open. For example, when I open a file it displays the complete hour and twenty minute file the width of the screen. Consequently, the time scale is very compressed. How can I expand the scale to display the same waveform detail I had when it was originally recorded? I do not want to change any of the characteristics of the file just want to be able to see more detail.

You need to “zoom in”.
There are several ways to do that. I like to use “Ctrl + Mouse Wheel”, but other methods are described here: Zooming Overview - Audacity Manual