How to Change the Color of Several Columns in a Keynote Bar Chart​​

You need two data series.

In Keynote charts, all values for a series will be in the same color.

To get a different color for the second set of columns they need to be in a different series.

Here's an example of how I did it:

I've used two series - the first series only has values for April through July, and the second series has values for August through September.

Setting the chart type to Stacked Column gives you the effect you're looking for.

> Do you know how to change the position of bar of average?

There is no control over the position of labels for reference lines (assuming that's how you're achieving that line).

The only other way to do that is to not label the line automatically, but overlay a text object over the chart with the label text.