I open several .mp3 files in audacity, one per instance and the scrollbars are different for each instance.
One instance will have just a vertical scrollbar; another will have just a horizontal one. Some have both and one or two have none.
Why is this ???
I would prefer to have none at all - maybe done via a configuration parameter.
The scrollbars depend on the zoom level and the size of your Audacity workspace. To disable them entirely, you could try tweaking the interface preferences to adjust the default view settings.