My quickbooks is saying it can't access my customer list and won't let me write an estimate.

Welcome to the Community, tsharbrough7. I have some troubleshooting steps to help with your issue regarding accessing the customer list and creating an estimate.

Excessive data stored on your regular browser can result in system performance issues that hinder you from performing tasks optimally. To resolve this, let's perform some troubleshooting procedures to eliminate this. You can use an incognito or private window to open your QBO account. It prevents the website from using corrupted cache files.

Here are the keyboard shortcuts for your reference:

• Google Chrome: Ctrl + Shift + N
• Mozilla Firefox: Ctrl + Shift + P
• Microsoft Edge: Ctrl + Shift + P
• Safari: Command + Shift + N
  
  

Once you've accessed the customer list and estimate using the incognito window, please return to your regular browser and clear its cache to refresh the website's preferences. For the best and most secure experience, you could also consider using other supported browsers or devices.

Moreover, when the estimate is approved, flip it to an invoice by following this reference: Convert an estimate into an invoice in QuickBooks Online.

Here's an additional article that provides instructions on managing customers in QuickBooks Online, including how to modify, delete, and merge clients within the program: Manage customers in QuickBooks Online.

Following these measures will help you get back to managing your business smoothly. If you have other questions or concerns about performing tasks in QuickBooks, let me know by clicking the Reply button. I'll get back to you to answer them, tsharbrough7.