When setting up your company in Big Red Book I personally do not recommend using the opening balances feature. Heres Why:
First Lets look at the trial balance as is:

Big Red Book Trial Balance

Now lets Set up a new supplier and add an opening balance.
First Press the F3 Hot Key to enter the suppliers Module

Big Red Book Supplier Module

Now click add to add a new supplier
Inside the new supplier screen fill in the details as normal

Big Red Book new supplier

Now I click opening balance and enter the details (I dont recommend doing this Im doing it for example purposes)

Big Red Book Op Balance

Ok now I will save that and recheck the trial balance

Big Red Book Trial Balance 2

As you can see the software has dumped the suppliers opening balance into 999 Retained profits. For this reason I recommend entering your opening balances in as invoices in the supplier module.

The same applies to debtor opening balances.

Do My Books provides nationwide training on Big Red Book if you require any further information please do not hesitate to contact Ralph on
bigredbook@domybooks.ie
or 086-3336665