You can adjust how many generations of your ancestors are seen by increasing or decreasing the 'Parents' variable at the bottom of the screen. To adjust how many generations of decendants are seen, change the value of the 'Children' variable. To see more cousins, increase the value of 'Others’, etc.
There is a limitation to the tree view that only allows you to display the aunts or uncles of the selected person, not great aunts/uncles etc.
To actually 'see' more of the tree you can click on the + or - magnifying glasses to zoom in/out.