To Zoom In the waveform at the current position press the "Zoom In" button of the toolbar that is on the upper side of the screen.
Alternatively, you can select "Zoom In" from the "View" menu.
How to Zoom Out
To Zoom Out the waveform at the current position press the "Zoom Out" button of the toolbar that is on the upper side of the screen.
Alternatively, you can select "Zoom Out" from the "View" menu.
How to Fit Screen
To zoom the waveform so that its width fits the current screen's width press on the "Fit Screen" button on the toolbar that is on the upper side of the screen.
Alternatively, you can select "Fit Window" from the "View" menu.
How to Zoom Into Selection
To zoom into the current selection press on the "Fit Selection" button of the toolbar that is on the upper side of the screen.
Alternatively, you can select "Zoom to Selection" from the "View" menu.
How to Zoom to Normal
To zoom back to normal select "Zoom Normal" from the "View" menu.
How to use the Zoom Tool
You can also use the "Zoom Tool" with which you can select the waveform's area you want to zoom in.
To use the "Zoom Tool" press on the "Zoom Tool" button of the toolbar that is on the upper side of the screen.
Alternatively, you can select "Zoom Tool" from the "View" menu.
Afterwards, select the area of the waveform you want to zoom into.
Lastly, do not forget to deselect and press on the "Zoom Tool" button again to return to normal functioning.