Sandra Yoanidis said:

is there any way to customize the income statement reports.

Customizations can be saved by using the 'Save Template' button at the top right of the configuration screen.

Sandra Yoanidis said:

I would like to set up various reports to show different amounts of detail. 

Sage 50 doesn't use a hierarchical chart of accounts, but you can open the sheet in Excel and customize it, or use an Excel sheet where you paste the TB in one tab and use links to pull the data into other tabs.  

Also, a number of direct-to-Excel reports are available under Reports | Microsoft Office.   Customizing these can be a bit of a bear, since they use SQL and VBA.  A 'Third-party' Excell add-in reporting tool that might do what you need is XLGL.

Sandra Yoanidis said:

Also, is there a way to amalgamate various accounts into one for historical data? 

I'm not sure, you can specify which historical accounts 'map' forward to current years for comparison reporting.  I haven't tried multiple historical accounts mapped into one account in the current year to see what happens.