Hi Wayne,
To achieve the desired result, you need to model the back end universe accordingly, as Tammy has pointed out. Based on your Design Studio screenshot, my impression is that your universe has just one measure (Gross Trans.) and one dimension (combining year and month in YYYY-MM format). To clarify/confirm this it would be helpful if you shared a screenshot of the Design Studio Query Panel for your universe data source.
I will describe two approaches just to give you a better understanding of how the back end modelling influences the end result. However, the first approach is the one that will achieve the requirement based on your first screenshot.
Both approaches apply a chart type of Column and require the single YYYY-MM dimension to be split into two separate dimensions (fields). Also, if you would like to display the months as abbreviated texts such as "Jan", "Feb" etc., you will need to define two fields in your universe one for the month key ("01", "02" etc.) and another for the month text ("Jan", "Feb" etc.). The month key is required so the chart x-axis labels can be sorted in the correct order. It is not possible to convert the current YYYY-MM dimension to text label format (i.e. "Jan", "Feb" etc.) in Design Studio because there is no way to assign these changes to the chart since the data source is assigned directly to the chart.
Please note that in my examples I have used the dimension Weekday instead of Month for illustrative purposes due to the data available in my system. However, the same principle will apply to a Month dimension.
Approach 1 - One measure for each year
Under this approach, the data source is modelled as follows:
The chart properties are set like this:
And the result is this (which corresponds to your requirement):
Approach 2 - One measure only
Under this approach, the data source is modelled as follows:
The chart properties are set like this:
And the result is this:
Hope that helps,
Mustafa.