Q:

How do I set Handbrake to default to mkv Matroska format?

I use Handbrake to rip DVDs to Matroska mkv format files, but I keep forgetting to choose Matroska from the format dropdown for each video. 
I can't find any way to set this as the default. It looks like I should be able to create a preset that uses Matroska, but I can't see how.
Is there a way? 
Using Handbrake 0.10

A:

Settings like the format are tied to the individual presets. You can either modify / create a preset, or make one of the default Matroska presets your default.
It looks like the preset management has moved a bit between versions. Here it is in 0.9.9 (xubuntu 14.04):

NOTE: in screenshot above the arrow points to all 3 buttons below the preset list.
Here it is in 1.0.1 (manjaro update 2017-01-30):

