Bar graph

I have a chart and one bar has a total of 300. When I create the graph the total goes on increments of 20 which is great so the chart is not so big. But when I go to view the graph within the application it goes in increments of 2 and then makes the graph to big to view. Now i have to scroll down so much. How can I keep it at the amount of increments I choose. Thank you.