my query is regarding the AMRF. Do I have to convert my AMRF into an ARF as my pension income exceeds the threshold or can I leave as an AMRF until as such time, it suits me to convert to an ARF?
You don't have a choice in the matter. From the Revenue Pensions Manual.
Firstly, where such individuals have guaranteed annual pension income of at least €12,700 on or after 27 March 2013 (the date of passing of Finance Act 2013) any AMRF immediately becomes an ARF.