I don’t have any personal experience with this but I would think that it would work the same way as htaccess files (where it takes the ‘global’ file, unless something further down the file structure overrides it). So, if you were to replicate the php.ini file and just change the max upload size?
Make sure that the php is being applied, also 1 megabyte is pretty small.
Create a PHP test file that contains the following code in the same directory where the .htaccess file is located:
<?php phpinfo(); ?>
Then look for two variables in the info that returns:
upload_max_filesize post_max_size
post_max_size needs to be larger than upload_max_filesize. It can be set in htaccess as well.