In Budgyt, formulas live in the budget in which they were created, but once built they can be copied from one budget to another.
If you Clone a budget, the formulas will be included in the clone, but if you created a new blank budget, and want it to use some of the formulas you have already created elsewhere, you can use the Copy Formulas feature.
Go to Data/Formulas > Copy Data, and choose the Copy Formulas option from the menu at the top left. Now you can choose which of your C2C, FOA, and Rule formulas you wish to copy across, and once copied they will immediately start working on your data.
One note of caution - when you copy formulas, the ones that you choose to copy will replace all the formulas in the target budget, they will not just be added to any that are already there.