Welcome to the QuickBooks Community, dev-accounts-bit. Please know that we aim to deliver customer satisfaction at all times that's why we address an issue as soon as possible. With this, may I ask for additional information on what are you referring to merge all QuickBooks accounts in one app? Are you trying to merge QuickBooks accounts to one company or various bank accounts into one account? I appreciate you for sharing extra details so I can present an accurate steps.
For now, I'm adding this article to further guide you in effectively working your business using QBO: Help guide for QuickBooks Online. It includes topics about accounting, banking, and payments.
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