All text-objects have a font defined by for example "Application Font". Therefore it will keep the stored fontsize in pixels when you change the monitor resolution or resize your front panel.
So if you want to change the size of the used fonts, go to Tools/Options.../Fonts and change the desired font. Notice that you have to restart LabVIEW to see the changes. This is because the information has been appended to the LabVIEW.ini file. This means that you can get the same effect by simply adding the line (for example: appFont="0" 20) by hand.
Good luck!
- Philip Courtois, Thinkbot Solutions