Let's say we have a waterfall's chart. In between forecast and actual, there are positive and negative values. But the values are small. Therefore, the chart visually may not represent the changes in between forecast and actual.

Alex,

Currently, there is not a way to change the axis of the charts. We can take off the 0 from the chart.  The other piece of information is that you could zoom into a chart and it will automatically adjust the chart.  

You may want to think about submitting a support request (enhancement request) to allow within the properties to adjust the chart axis

-Ryan