As I've mentioned above SMath Studio has no any user interface for changing text formatting. Unfortunately there is no any way within a program to change a font. But you can use a small trick:
1) Create a worksheet;
2) Create a text region;
3) Save created content as a *.sm file;
4) Open created file with a Notepad or any other simple text editor;
5) Find lines like:
Code: <region id="1" left="198" top="297" width="83" height="27" color="#000000" background-color="#ffffff" font-size="12">
<text lang="rus">
<p>My test text</p>
</text>
</region>
6) Change it to:
Code: <region id="1" left="198" top="297" width="83" height="27" color="#000000" background-color="#ffffff" font-size="12">
<text lang="rus">
<p font-name="Arial">My test text</p>
</text>
</region>
(see
<p font-name="Arial">My test text</p> line)
7) Save changes in text editor;
8) Open the result file with SMath Studio.
Hope it will help you.
Regards.