Font size setup problem when exporting the figure

Hi every one, I've got trouble with font size when exporting figure to any other format that .fig. I need to set bigger font and save the image. Font magnifiaction is done correctly but after saving image, the font is always small. I guess it's the problem with the figure because other figures can be exported correctly, but I cannot find out what's the problem.

I attach the figure.

Thank you very much

Tobias