database diagram

Question

i am about to create a database diagram but this error appears. what does this mean and what should i do? tnx This database does not have a valid dbo user or you do not have permissions to impersonate the dbo user, so database diagramming is not available. Ensure the dbo account is valid and ensure that you have impersonate permission on the dbo account. i remembered changing my computer name. and what i see in the dbo owner is the previous computer name. so, how will i change it to current name?