In Campaign Manager, your account is comprised of advertisers, sites, campaigns, and user profiles. Your settings determine which features are available on this account, and how they work.
Each Campaign Manager account is separate. Nothing is shared across accounts: advertisers, sites, campaigns, user profiles, Floodlight configurations, and other settings are not shared.
However, you can use the same Google Account to access all your Campaign Manager accounts. Simply create a user profile in each Campaign Manager account and associate it with the same Google Account.
Multiple accounts: Some Campaign Manager customers use one account for all of their advertisers and campaigns. For more complex business needs, it can be useful to create multiple Campaign Manager accounts. For example, a large advertising agency might use separate account to manage its major advertisers, or to organize campaigns into major verticals that correspond with the agency's organizational structure. Typically, the account structure is determined when your company begins using Campaign Manager, in close consultation with a Google Marketing Platform representative. To create additional accounts, contact support.
Account permissions determine what kinds of features and data are available in your Campaign Manager account. If you do not enable access at the account level, no user in the account will have access. However, just because you enable something here doesn't mean every user can have access. You can limit the access of individual users with user role permissions and user profile filters.