Your need for an accounting platform that doesn't constantly change is understandable, Gareth. It appears that these ongoing challenges have pushed you to seek a solution that fits your business needs.

To secure a copy of your historical data, you can export your report (depending on the transaction you need) to Excel. Here's how:

1. Open your QuickBooks account.
2. Go to the Reports menu, then the Standards tab.
3. Choose the report that provides the data you need.
4. Modify the Report period accordingly.
5. Click the Export icon and select the Export to Excel option.
   • Modern reporting interface:
     
   • Classic reporting interface:
     

Another way is to use the Export Data feature to move your reports or lists outside of QuickBooks:

1. Click the Gear icon.
2. Select Export data.
3. Tick the Reports or Lists you wish to export.
4. For Reports, you'll need to choose the appropriate date range.
5. Hit Export to Excel.
   
   

Aside from your reports and lists, you can also save a copy of your reconciliation data. Check this resource for more details: View, print, or export a reconciliation report in QuickBooks Online.

Should you have more inquiries, please revisit this thread.