Change the upload size

To change the upload size on Apache with PHP, edit file:

/etc/php/7.0/apache2/php.ini

The above is in case you run Apache on a Debian machine and you run PHP 7.0
It’s possible your php.ini is located somewhere else
Do a locate php.ini to find your file

Look for:

; Maximum allowed size for uploaded files.
; http://php.net/upload-max-filesize
upload_max_filesize = 2M

; Maximum size of POST data that PHP will accept.
; Its value may be 0 to disable the limit. It is ignored if POST data reading
; is disabled through enable_post_data_reading.
; http://php.net/post-max-size
post_max_size = 8M

And change the above values in bold to your needs.
Save your file and reload Apache
On Debian: /etc/init.d/apache2 reload