Upload more than 512 MB on NextCloud

i have installed nextcloud on ubuntu via app store (ubuntu software app) im using the latest version 26, i noticed that the upload size is set to default 512 MB but i want to upload single file sized 4 GB.

i have noticed that this issue can be rectified by editing (configuring PHP) unfortunately i do not have the file and folder www in Var is not available, it seems odd because nextrcloud require PHP and Apache to run, so how i can solve the limitation of upload file size.