I’ve recently ‘upgraded’ to a Seniors Myki, which meant I did some reading on the Myki site.  I discovered this gem…

Why does the information displayed on the reader vanish too quickly for me to read it?

The information showing your card balance, and the amount deducted for your journey, will be displayed for as long as you hold your card to the reader, so hold it up for longer if you want to check that information.

So hold your Myki on the reader and WAIT…it stays on the display.  Of course its not a great idea to do this in busy times.  Give it a go