This is usually due to the revision number specified in the upload.
Financials does not have a specific forecast area for nominal revisions. Instead, the system works with the method that the revision with the highest number is the actual budget, while any revisions with a lower number are forecasts.
If you have found that your forecast upload has affected your actual nominal budgets, please proceed as follows:
Open the current forecast upload sheet
Leave the revision number as it is and upload the correct actual figures
Change the revision number to be lower, and upload the forecast figures
Essentially - the revision with the highest number will always affect the actual budget figure