The file upload submission settings in Website administration - Plugins defines max upload size. The default setting is set to 1 MB.

General princip for file handling is moodle is that There is a hierarchical setting on system level - course level and activity level for file upload limitations. The plugin setting on system lebvel should be a default setting that can be overwritten by course limitation and on activity level.

In assign module the site wide plugin setting overwrites settings in courses and activities.

If on course level upload up to 30 MB for files is possible, in assignments the max upoad size is set to 1 MB and can not be changed to a larger size if plugin definition is not changed.

Please change the plugin settings to default size because the plugin settings normally are default setting.

If this is not a bug, the default setting should be unlimited because its not expected to reduce it to 1 MB. Also this setting should be described on interface because the settings are handled different to other locations.