Not applicable

In general.  it not a good idea to mark or edit reconcila...

In general.  it not a good idea to mark or edit reconcilating items in the QB register.
Those are best done in the bank reconcilation program.

suggustion:   Do a backup before doing any more work.

You have a decison to make how important is it to correct the prior period.
a quick and dirty way.   
Enter an adjustment to get the prior bank balance to equal your new correct balance.   Then make an offseting adjustment in the current month.
then   reconcilite to the correct month bank statement.    Next clear the corrected deposit(s) , and make a new adjustment which clears all the corrections and edits.

2.  the other way.   Right down the ending balance.  then carefully enter the correct deposits from the prior period, and edit the prior adjusting entry. to get the ending balance equal.    As to clearing the deposits, do it in the current months bank reconcilation..   It usally not a issue, if one bank account has open items,

Also QB really only reconciles to the ending balance.   When the balance is zero. that is all that is needed.   The begining balance is simply the sum ofall preious cleared items.   the beginning balance is not really factored in the reconcilation.   As long as your current month bank statement and clear amount per bank reconcilation equal. that is all that counts.

With quickbooks,  it is possible to enter transactions dated in prior months, and as long as that transaction did not actually clear the bank.  There will be no issues with the bank reconciliation.     Or in other QB only reconciles to the bank statement balance.  QB does not really track the open items, like we normally are used to.