Under the Measures menu, you can select next to each variable whether to plot it on left or right Y axis. Selecting just one axis for all variables will plot them all on one scale.

I dont mind if its on the left or right Y axis. But I want one just one axis for the whole graph, not one per bar.

You're using paning instead of splitting. There is a scale for every pane.

In the split menu, you can add multiple hierarchies of split-by's to replicate the same as paning, but with shared axes.

Ah ha!! Thats it! Thanks