Unable to share web map with everyone

[SPNIOrganization]

Hi,
I have an organization account. I made a web map which contains only basemap.
In the sharing options on arcgis.com viewer I don't have the option "everyone" and on explorer online I can see the option but can not choose it.
any idea why this is happening?

thanks,
Dikla.

[TimothieBiggs]

It could be that your site is configured so that this option is disabled. Anyone with the role 'administrator' should be able to confirm this for you.