Since 1.2, there is the "plot style" button in the main menu that permits to change the overall style of a plot.
The know styles are the ones found in the ioda.style (see Customization, ioda.style file).
For example choose examples/hrand :
Then choose "plot style" from the main menu :
Choose "all" to apply the new style to all plots, and then choose "ROOT_default" in :
You should see :
(which is not necessarily our preferred plot style !).
You can customize per plot by choosing a plot index instead of "all" and have for example the hippodraw style for the first plot and the ROOT style for the second plot :