The Input Journal Entries area was never really designed as an area for farmers to make changes. It was designed more for an area that accountants could work in. The better way of fixing previous entries is to go through the Payments & Purchases or Income & Sales areas.
For example, assume you record a purchase and you put $1,000 to Repairs - Equipment and you meant for it to go to Repairs - Bldg. You could adjust the balances in these accounts by going into Payments and Purchases and select the Purchase Option for Expense & Other Payments and enter a negative $1,000 and select Repairs - Equipment. You could then go to the Purchase option for Expense & Other Payments again and enter a positive $1,000 and select Repairs - Bldg. You can either use the same vendor as you originally used, or you can create a new vendor called "Adjustments". Be sure to set the date back to the date of the original purchase. This transaction can be recorded without writing a check or setting up a payable or loan. Using negatives for the various purchase and sales options is a good way to fix mistakes and adjust account balances.
If you still wish to use Input Journal Entries box, page 258 of your Farm Fund$ manual gives an explanation of whether you should debit or credit an account to increase/decrease its balance.