If you are seeing the error "Failed To Insert Media" in WordPress then chances are you have a permissions issue on your website. You could also experience issues with trying to install a plugin or a theme. This is an easy fix, so just follow along here.
Open FTP Program To Edit File Permissions
Open up your favorite FTP editor. I have several I have talked about in the past that I like. The post is here HTML and FTP Client Editors (a1websitepro.com) For this demonstration, I am going to use FileZilla because we can get the job done quickly. If you do not have an FTP client, then you can just open your cPanel, Plesk panel or some file explorer that is on your server.Changing Permissions For Folders
After connecting to your server with your FTP client then look for the wp-content folder. Right click on it and then click "File Permissions".
You will see a box appear like this. Make sure your wp-content folder has 755 permissions.
Make sure all your folders have the 755 permissions. Also make sure the wp-content/uploads folder and all the folders in that folder has the 755 permissions. If you need more help there is a video on the next page.