Make sure that the "Opening Balance" transaction in your register - always is the oldest transaction by Date - its amount matches the bank statement balance shown on that day - the transaction is marked "R"(reconciled) in the "Clr" column - occurs only once in your register- if you owe money in a credit card account, the Opening Balance transaction as shown in the register must be a negative amount, e.g., $-123.45
If the Opening Balance isn't correct, your register balance on any given day will never match the bank's balance on the same date.
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Getting Started with Quicken for Mac https://www.quicken.com/complete-guide-getting-started-quicken-2018-mac https://www.quicken.com/quicken-tips with links to more information and videos
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