Make the change in the sub account and then click Apply to popup the Apply Changes dialog.

I tried that.  It did not work

Are you changing the Description or the Short Description for the Sub Account?  For Sub Accounts, the Short Description is what is used as part of the Account Description.  

Note in the Apply Changes grid for Sub Accounts it is the Short Description changes that can be applied.

Are you changing the Description or the Short Description for the Sub Account?  For Sub Accounts, the Short Description is what is used as part of the Account Description.  

Note in the Apply Changes grid for Sub Accounts it is the Short Description changes that can be applied.

Yes, I changed both.  There is a note on one of the tutorials that said if you have updated the account name in account maintenance than the Apply Changes will not work.  I do not think we updated the description in account maintenance, but all our accounts were added through an import when we converted. 

I was going to mention that exact note.  If the account description has been changed the Apply will skip those records.

What was imported may not have followed the defaults for creating an account description from the Main Account Description + Sub Account Description(s).  This includes the separators that are defined in Account Structure Maintenance.