Hello Ismael,
   - How can I
increase the size of the used fonts?
 I can't neither find any hint in the *cfg-Files nor while searching with
 google.
 The fonts are so small that I hardliy can use the program. 
 I am afraid you mean fonts, not soundfonts, 
 You're totally right!
  so go apt-get install
 xfonts.*transcoded and restart your X server. 
This doesn't make a difference.
Regards Helmut
(mlist(a)hk-vision.de)