This tutorial will give you a general explanation on when you should be opening or closing your accounts.
This is merely a guideline as to when you should open an account and when you should manually close an account.
It's going to be dependent on the specific scenario that you're dealing with.
If I need to open an account
This would only be relevant if the account has already been invoiced or closed manually.
If you need to open your account, generally this would be because you want to change something on the account after an invoice has been generated. If the invoice has been generated, this would mean that the account would be closed and accounting entries have been generated.
To find out what to do if an account has already been invoiced, click here.
If you need to manually close an account.
You would only need to manually close an account if you do not intend on invoicing the account.
This may be necessary where you have given "freebie" accommodation and so you would not be invoicing the account.
You may also need to manually close an account if the system does not automatically close the account for you in certain circumstances.