When I use "Magic" to make graphs consistent, the axis range and intervals don't change.

When Prism applies "Magic" to make axes consistent, it first looks to see if the range of the example graph was set manually or automatically. If automatically, then it also makes the range of the other graphs to an automatic range, which means the actual range might vary from graph to graph. If the example graph has a range set manually, then the exact range and interval are used to change all the selected graphs.

Double click on the axis of your example graph, and turn off the 'auto' setting for range, and it will work fine.