There is one full post and the linked titles to 8 others on your front page. All your readers have to do is click on the titles to read the full post so luckily this isn’t a really awful problem. Actually this may be a good thing because having too many posts on the front page can really make page loading a long tooth grinding experience.
If you have changed this to 10 on your Reading page above and then clicked “update options” and it didn’t work there are two possibilities. (1) The theme is not designed to display more than one full post on the front page. (2) This isn’t the case and you are experiencing the manifestations of a bug or glitch of some sort. You’ll have to send in a feedback to staff and include a link back to this thread.