Blog not showing excerpt but full article on main page

Hi there. So I have a wordpress site – not paying to host it elsewhere, just a native free wordpress site using the twothousandfourteeen theme. I have been super frustrated because all the help files say to edit index.php to fix the issue of showing the excerpt vs. full post (and the dang settings->reading where you can select that doesn’t seem to do anything).

I tried creating a “home” page so i could use that and a different page for the blogs like folks reccomended, but couldn’t get the home page to show any blogs (summary or not)… So back to letting wordpress show the blog as the summary but just don’t want the full article posting.

So 1) I would like to know how one accesses the source files for their site if you are using a free wordpress one. Nowhere seems to tell me (and what to use to edit it). I don’t mind staring at code ??
2) Any idea how to fix this issue given the information above?

My site is: https://fishfoodandfun.wordpress.com/

Any help appreciated. I thought it was supposed to be pretty straightforward but apparently stumps even a computer science major!
Thanks!