When you try to upload a large files to wordpress based site, you receive a message saying that the file size is too large. If you receive this message and if you want to increase the file size, you will need to increase the maximum file size by modifying the php.ini file.
On a cPanel based website, login to cPanel and go to Software/Services section. Click PHP Config icon.
Then go to php X.X (Single php.ini) file. choose the version of php you want and click save.
Now when you go to your web folder (public_html), you will see a file called php.ini. You need to edit the php.ini file. Look for Post_max_size and increase the number to the maximum file size you want to. Also, look for upload_max_filesize and increase the size there as well. Save the file.
Now you should be able to upload larger file size to your wordpress blog.