chicitup on "prevent all posts appearing in categories"

I am new to wordpress and at coding! I have 3 categories but all the posts are showing in all the categories. I have tried deactivating plugins and changed theme from twenty fourteen to twenty thirteen, and re installed wordpress. Still can't get the posts to just appear in the category that is assigned to them.

Please post a link to your site.

what is your setting in the permalinks:
https://codex.wordpress.org/Using_Permalinks

this is my site http://www.shabbychicspain.com

http://shabbychicspain.com/archives/123
I this is the permalinks setting numeric

I changed permalinks settings to post name. But still not solved. I am very much a leaer sorry!

I have changed the theme to diamond which I like, but the problem still persists