WebPlus X4: Master Page Title

Can someone please help !! Just recently published a new website . When we published after dificulty we noticed the font for the header in the master page needed changing . So we changed and republished but when viewing on our own computer on the internet it looks fine. But when viewing on other computers its still showing the old font( we have cleared history and refreshed browser ) . We have republished several times but it won't change . Any suggestions on how to fix ?? Is there something we are doing wrong ?

Thanks in advance