In some articles it doesnt recognizes the bold formatting and generally the formating of text is not quite so good. I use font size 10. Can you tell me how I can format the text to appear correctly. I had'nt such problem whith content article of joomla.

Here's two contents to see what i mean (the articles is in greek language):

Article 1

Article 2
 

I appreciate any help

Thanks

It is probably another css file overwriting what you are doing...

And what can i do to fix it?

The text you have put in the article has many tags that are not needed, like spans with style on them, etc. Either choose to clean the text before pasting it in the item box on the backend or you could enable the introtext clean up code from K2 general parameters and just put which tags you want to allow for the text.