Do you want to increase or set the value of upload maximum file size in PHP. Create a php.ini files in user root path and add following lines.

​# vim php.ini

upload_max_filesize = 128M
post_max_size = 128M
memory_limit = 64M

upload_max_filesize : The maximum size of an uploaded file. By default upload_max_filesize is 2MB. 

post_max_size : Neet to set maximum size of post data allowed, to upload large files and post_max_size values must be larger than upload size.

memory_limit : Need to set maximum amount of memory size, upload value is calculated in bytes. If you have set this directive to -1

Example : memory_limit = -1 

If you dont have permission or changes for the users add the below line in .htaccess 

suPHP_ConfigPath /home/username/public_html

Finally, restart your apache server if not reflect.