With the release of Quicken Classic for Mac 9.2, budget rollovers have been added (yay!). However, there is currently no way to manually edit the rolled over amounts like there is in Quicken for Windows:
This is really helpful for setting up initial amounts of "rolled over" funds that users may have tracked outside of Quicken due to the lack of budget rollovers prior to version 9.2. It is also useful for moving rolled over funds around (for example, if a category has a lot of rolled over funds that have stacked up, being able to "move" some of those rolled over funds into another category where the funds are needed—similar to moving physical cash from one envelope to another).