Hi Nicholas,
It’s impossible for you to change shape for all call out shapes across all the slides, you just can change the shape’s style by right-clicking the edited shape, then choose Apply to All Shape Objects > Style.
When recording software simulation, you can change the default settings for objects such as cursor paths, shapes, and correct/incorrect messages (call out boxes). Please take a look at our tutorial: https://atomisystems.com/tutorials/ap7/setting-default-objects-when-recording-simulation/ to see how.
Please let us know if you have any more questions or concerns.
Best regards.