Apologies for the confusion - I have been informed that this was recently added by our development team as part of recent performance updates. Very few users will need to return data going back further than 2 years when loading the bank statement page, so this is narrowed down to help improve the performance here.
You can however override this to view that data, it just needs to be done manually. To display transactions beyond this range, if you click on Search, you can enter a From date as far back as required (e.g. 01/01/2010), and this will change the results for you.
Hope this helps.