Graph Builder: How do I reduce spacing between bars?

[#1]

I've got the following graph, in which width and spacing in the two panels (experiments here) are automatically set so that the two panels are the same size. i want both panels to have the same bars widths and spacing (which would make the right panel narrower than the left)  i've here changed bar widths in the right panel (customize > bar > width proportion) to match those on the left and i now want to reduce spacing between bars (and in the margins) so that both panels are the same with regards to these two attributes. 

any ideas?

thanks

[#2]

Right click on the graph and choose "Customize"
In the Customize window select Bar and then change the Width Proportion

[#3]

as i wrote in the posting, i did what you suggested to change the bar widths. reducing spacing between bars is the step i'm having problems figuring out

[#4]

Go to the x axis.  Move to the right on the axis until the grabber(hand) changes from vertical to horizontal. Click and hold and move the cursor to the left.  It will squeeze the axis down in size, reducing the space between the bars.

[#5]

that works to reduce bar width and spacing but then I have a big gap between my bar and the edge of the panel. any suggestions on how to fit the panel to the contents?