Are you on a adedicated server? Ask your host to please tell you where the php.ini is located and where can you make the changes. If you are on a shared account then your host will have to do this for you.

Most of the time your host will still make the required changes for you if you just ask them to do it. It is not hard at all if you have access to it.

If you have WHM then look in tweak settings, or php settings.