Can I modify Business Snapshot to display previous fiscal with last fiscal income and expense comparison?

You've reached the right place for help. I'd be happy to help with creating a yearly comparison report in QuickBooks, RWilliscroft.

The Business Snapshot report is only capable of showing data for This Year-to-date, Last Month, Last Quarter, and Last Year. However the option to view both of them simultaneously for Business Snapshot t. I recommend printing both of them out so you can compare them side-by-side if that's your goal. You can do this in just a few clicks, by selecting the small printer icon on the upper right-hand side of the report. 

We can also view data for a wider date range by checking out the other reports available in the Reports center. Just run a Profit and Loss report. To do this, click Reports from the left menu and search for the Profit and Loss report. Once you're on the report page, enter the dates you're looking for in the filter box. From there, click Customize and navigate to Rows/Columns. Then, change the Columns to Year and click Run report to see the info you're looking for. 

Here's an article you can refer to for more details about customizing reports in QuickBooks. I've got a link here that contains articles on running balance sheets and profit and loss reports to manage your business: Financial reports.

Keep in touch if you need any more assistance with this, or if there's something else I can do for you. I've got your back. You have a good one.