QB Issue Resolution:

It uses whatever scanner is selected in your Apple->System Preferences. Note that some scanners don’t work because they don’t implement the normal Apple TWAIN driver (Fujitsu snapscan is one). For those just scan to a PDF and then attach the PDF by dragging it over. (This helps, too, on buggy scanner drivers, which sometimes crash)

Resolution for Issue 'How can I change which scanner Quickbooks for Mac selects?' available: Yes (Solved).
Source: Intuit Community forum.

How can I change which scanner Quickbooks for Mac selects?: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

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