Hi @chris1,
Great questions and we agree on the naming. We’re still in the process of cleaning up/transitioning these tools after some major product updates from the summer.
The guide for the Tiller Budget is here and talks through the way to add future months.
The Rollover To will move from month to month automatically as new months are generated. We just don’t automatically set it for the first period (in your case September) in case you want it to be different in Oct. Whatever is in the Rollover To column on Categories will be used in the current budgeting period so if that doesn’t change, they’ll be exactly the same each month.
I don’t recommend rearranging the columns in that sheet.