Hello MarkI,
The way you can change the default font for either the "Artistic Text" or "Paragraph Text" in CorelDRAW is the following:
1. Click on the text tool in the toolbar on the left of the screen but DON'T click anywhere on the page
2. This will change the "Property Bar" at the top of the screen to reflect the tools specific for the text, including a drop down menu with a list of all the installed fonts on your machine.
3. Click on the arrow to expand the drop down list of fonts, select the font you want to make your default font. When you do this a dialogue box will appear with the title "Text Attributes" and will say "Changing text properties when nothing is selected will modify the attributes used by the text tools when creating new objects." and "Click on the boxes below to choose which tools will receive new default settings." and it will give you the options of "Artistic text" and "Paragraph text" Select which of the two text types you'd like to change the default for and and hit "ok".
4. That's it you're done. If you don't understand my instructions let me know and i will make you some diagrams. I hope this helps.
NOTE: By the way you can use the same technique with other defautls such as colour or outline by selecting that tool in the toolbox first