Is it possible for the reports to show how they have been ran, cash or accrual?

I'll say it's a Yes and a No to your question, ndunne.

The availability of the Accounting method (cash or accrual) option depends on the report. You can see it in most of the reports, but not all. 

Some reports without it are using the default accounting method on your company settings.

1. Click the Gear icon in the upper-right corner and select Account and Settings.
2. Select the Advanced tab and go to the Accounting section.
3. Check the Accounting method. You can change it if necessary. 
4. Click Save and Done.

If you're opening a report that doesn't have the Accounting method option, you might need to click the associated amounts.  This is a way to verify the accounting method of the report. You can also use a different report that can give you the same data.

You can give us an overview of the report you pull up, too. This would help us know what alternatives we can give. Thanks in advance!