You need to change the upload_max_filesize directive in php.ini . Contact your server admin for help on this.
Try searching for “file upload limit” (along those lines) as well.
Change this field too:
post_max_size
I had to put a php.ini file with the settings in the wp-admin directory.
Since I’m on dial-up, I haven’t tested whether that’s the only necessary location or if the one I have in the uploads directory is also needed. I do know that the latter alone did not work.
My blog is in a subdirectory of my site, so WP’s behavior in this regard may be different.
I have a simple workaround without messing with the code. First, upload the file to content—>uploads. Your URL if in the root will then be http:www.yourdomain.com/wp-content/uploads/2007/[subfile if any]/filename.mp3
Link your visual word to that URL and voila, your mp3 will play just fine!