[size=9]This is really terrible...
this lettes are so small that using Deskzilla for all the day really hurt my eyes...

Theres no such an option to make them bigger in menu [b]and should be

Hello Mikolaj,

Thanks for your request: this issue has just got a severity kick: http://bugs.deskzilla.com/show_bug.cgi?id=132

Best regards,
Igor

Is there any manual way to set font size in Deskzilla?

Not right now, but we'll see if it's possible to include in Deskzilla 1.1 a simple command-line option to set the font size. Thanks for your concern!

Cheers,
Igor

Good news: Deskzilla 1.1 has a few things to alleviate this problem.

First of all, try to run it - if the font size in comments is still terrible, try to add "-Dfont.size.abs=11" as an option:

deskzilla.exe -J-Dfont.size.abs=11

or
java -Dfont.size.abs=11 -jar deskzilla.jar

Thanks!
Igor