If you are able to change your php.ini file, and you in fact do change it, you might be changing the settings to your entire server. You’d be changing the upload_max_filesize (as you said) and the post_max_filesize settings.
Depending on your host however, you might be able to change these settings in your .htaccess files, which could possibly allow you to have different settings per directory.
If editing the php.ini, just look for upload_max_filesize and post_max_filesize and raise the limits to whatever you need them to be. I think the defaults are 2MB.
You can also try editing .htaccess files like I said above. If you want to try that, just open up one and add something like this:
php_value upload_max_filesize 10M
php_value post_max_size 20M
Change the sizes to whatever is needed.