Alexander, if this is an imported project then the text has almost certainly been placed as an image during the conversion.  Place a text box over it, recreate the text/font/size etc, then you can remove the image.

If this is a new project, please advise,  because any text in the header or footer should be totally modifiable.

Esahc,

I make the new project. I can not modififate the size of fonts.

Tanks Esahc! I have done.

Hello Alexander, 

thank you for your message. 

Were you able to solve the issue?

Thank you. Kind regards.