Chart formating problem

Hi!

I have a simple bar chart in reverse order, and all axis values, labels and
titles formated at 9px weight.
When I re-open the document all of the mentioned text appears at 1px, what
forces me to format again back to 9px weight. And that repeats at every
re-opening.
I've searched the options in hope to find some check-box that always fix
things like this one but there isn't any.
Do you have any idea why those labels are so stubborn?

Thanks!
K.