I do not have problems to find my section on the map.
I know how to select the section on the map and then do fit-to-window on the map.
But when I do fit-to-window on the chart, nothing happens.
When I follow your instructions regarding the resizing of windows, I will have this view

Such a chart does not give me the information I want to have
When I cut a section out of the track, and make an activity of this section, I will have a chart like this

Such a chart tells me everything I want to know
But it is a lot of work to produce a chart like that.
I think it should be possible to zoom in on a section of a track in a shareware application like ST3+TrainingAnalysis by stretching the X-axis of the chart.It is possible in several freeware applications.
For instance. When I load the whole track in a freeware application like My Tourbook, I can easily zoom in on my section.
And I will have a chart like this with a few mouseclicks.

(do not ask me why the chart of TrainingAnalysis is different from the chart of My Tourbook)