Sorry to be the bearer of bad news, but you really want an analog ammeter, not a digital one. Fortunately, not a very expensive problem…
An analog ammeter, for units with only digital display. The digital display is not accurate. An analog ammeter may not be essential before your first test, but is a strongly recommended add-on. @donkjrdescribes how to add an analog ammeter.
The K40: Getting Started category has lots of useful information in it, if you haven’t seen it yet! Highly recommended!