You can set each level in your course to have different testing directions. This is relatively easy to do but you need to take a few things into account:
Testing directions apply to typing and tapping (aka 'rearrange the words') tests only. Multiple choice tests will switch testing directions as you progress through a level, and there is no way of editing this.
When you set a testing direction, you'll be asked what you want to test on, and what you want to be prompted with. This can seem a bit confusing if it's your first time creating a course. To make it simple, think of it this way: 'Tested on' means "what you will need to answer" and 'Prompted with' means "this will be the question".
To set the testing direction, simply go to your 'Editing' page on your course, and click 'Show' on the level you want to work on. At the top of the level you will see the 'Test on (language), prompt with (language)' option. Click on the pencil icon next to it to edit this.
You can choose testing directions from the columns available in your course (if you want to Test on- and/or Prompt with- Audio or Images, you will first have to add the relevant column in the course):
Don't forget to click 'Save'!
If you would like to test the same items in the opposite direction, simply Duplicate the level and change the testing direction accordingly.