MultiSite: edit in one place for entire install to inc file upload limit?

Hi,
I have a MultiSite, all sites are mine and I am the sole admin/backend user. I need to add some code to increase file upload limit – my host has increased it on their end.

I did a search about htaccess in a MultiSite, I am still unclear:
– There is one htaccess for each site.
– Is there a “master” htaccess that will override the subsites?
– Do I need to edit htaccess for each site?

I am still searching. I am learning, so info is highly valued.

PS I will add this to increase the file size upload limit:
https://tournasdimitrios1.wordpress.com/2011/06/09/increase-wordpress-upload-file-size-limit-2/

php_value upload_max_filesize 50M
php_value post_max_size 50M
php_value max_execution_time 800
php_value max_input_time 400

Thank you