Today we had to raise the size limit of owncloud to allow for files over 2mb to be uploaded.
It is a really easy process:
Under Debian or SUSE and their derivatives this file resides at /etc/php5/apache2/php.ini
On Windows, you can find this file within C:Program Files (x86)PHPPHP.ini
Set the following two parameters inside the php.ini to the same value as chosen inside the admin-section one step before:
upload_max_filesize = 16G (e.g., to stay consistent with the example value above)
post_max_size = 16G (e.g., to stay consistent with the example value above)
These details were taken from this documentation.