I have four different accounts setup in Outlook. I know that it is
possible to use a default signature for new messages and replies with
each account. However, when selecting New to start a new message,
naturally, it uses the default mail account and inserts the
corresponding signature.

However, when changing the sent from account in the Accounts drop
down, one would expect the "default" signature to be used; i.e.
Outlook would delete the signature that it initially inserted and
replace it with the default signature for the selected account.

This is not what happens. Seemingly, each time, the account is
changed, the default signature for the default mail account must be
manually deleted and the default signature for the selected account
inserted manually.

Does anyone know of a way to achieve the behavior I have described?