it works on the chart that you are working on. If you change to a different time frame you have to do it again
That only works for that one chart and timeframe. Once you go to a new timeframe it defaults back to Autoscale. I can't see a way to change this. A quick way to get the scale to what you want, is to left click while holding your mouse over the right axis of the chart and move your mouse up or down to extend or contract the scale.
Thanks Macal, this is better than esignal tech's suggestion of opening multiple charts for each time frames.