I have two problems,
a) my assets total correctly but on the other side of the balance sheet the liabilities and equity do not show one overall total as opposed top total Assets, and apparently I cannot edit the Group Equity
b) I started to use Manager in 2016, and then made a mistake with my opening balance, which I only discovered now. How can I correct this?
Starting balance equity The account "Starting balance sheet equity cannot be booked against.
Your help is appreciated
The presence of the Starting balance equity account shows that your software is far out of date. That was an automatic account used to force your books to balance when mistakes were made. That is why you cannot post to it. Such imbalances are now posted to Retained earnings, because if the rest of your setup is correct, that is the place they belong.
So, update your software.
After updating, to correct the starting balance, see this Guide: Enter starting balances | Manager. (If you try to correct the starting balance before updating, the Guide will not make sense.) Once starting balances are correctly entered, all should be well.