Edit Form not working properly

Hello,

A website has come in my hands that I didn’t build, in this website the logged in members can create in frontend their own posts and I had to add the feature of editing those posts too. So, I created an edit post form and displayed it. But, the thing is that the form instead of editing and updating the existing post creates a new one with the changes the user makes. So, there are two posts now, the original and a second one that has all the updates we made. Here I have to mention that the previous dev that created the website used a different plugin to add the create a post forms, but his edit post form didn’t work at all so I added this plugin in order to create an edit post form.

Secondly, I also face a problem with the button that uploads files. I need to see the files that already exist in post and I have to be able to upload or delete the old and the new files that I upload. But, the button does not recognize the uploaded files and it does not upload new even if at the begining it seems that it did.

Thank you for your time in advance.

The page I need help with: [log in to see the link]