Anyone know how to access older QB checking account statements? System only shows 18 months

You have to send a written request or phone request and have emailed or mailed to you. 

To access your older QuickBooks checking account statements, contact our QuickBooks Checking support team. I'll connect you to the right team to help you with your statements efficiently.

I agree with @KimAnnVA. Please note that the system displays statements from the past 18 months due to a focus on recent transactions. For older statements, I recommend contacting our QuickBooks checking support team. They can access your account and provide the specific statements you need. Here's how to contact them:

1. In your QuickBooks Online, go to Help. 
2. Choose Contact Us. 
3. Select a topic to be connected with the right expert and decide a preferred way to contact.

On the other hand, if you want to allocate funds from your QuickBooks Checking account into envelopes for future expenses, check out this article for more a guide: Create envelopes to set your funds aside with QuickBooks Checking.

After reaching out to the support team, you'll receive your past checking statements. I appreciate you for reaching out to us in the Community. If you have any further questions or need assistance, please feel free to let me know below.