Transfer a License
From the article: Use this form to request to transfer the ownership of a QuickBooks license to another user. You will receive an e-mail within 24 to 48 business hours after you submit your request regarding the status of the request.
Attaching documents in QuickBooks desktop shouldn’t affect the performance of the software. They are saved on the computer hard drive in a separate folder, and they are not included in a back up of the QuickBooks company file either so that backup file does not grow either. All attaching does in QuickBooks, is to enter a pointer to the hard drive location for the attachment folder.
If you experience slowness with QuickBooks, there may be other reasons like due to a large company file or network issues.
Change regional settings in Windows
From the article: QuickBooks requires the Windows regional settings to be set to the United States locale. Otherwise errors may occur such as unable to open QuickBooks (loading screen flashes and goes away) as well as QuickBooks has stopped working/responding…
Fix common installation errors using the QBInstall tool
From the article: This article is part of our content on Setting up QuickBooks Desktop.System requirements
Troubleshoot installation issues
The errors listed below can occur if your Operating System is damaged or one of the core Microsoft components that QuickBooks Desktop uses is unstable or not functioning correctly …
This error can also be caused if there are other versions of QuickBooks not running properly in the background. If you get this error, you’ll just have to end these processes in the task manager:
Press Ctrl + Alt + Delete on your keyboard.
Right-click QuickBooks 20XX and select Go to Processes.
Once the process is highlighted, just click the End Process button.