I have been using Pmail in single user mode.  I have just installed PMAIL 4.7 as a new install  and want to switch to multi user mode.  How do I do it. I didn't get the option at setup time

From the FAQs section of the manual, page 170:

I installed Pegasus Mail in Single-user mode but now I want to switch to Multi-user mode
because I need more than one user. How can I do this and keep all my existing mail files?

Follow these steps:
1: Run your single-user copy of Pegasus Mail, select "Help", then "About Pegasus
Mail". Click the "Info" button, and find the entry in the list called "Home mailbox loca-
tion". Note this directory down on a piece of paper, then cancel out of the dialog and quit
from Pegasus Mail immediately.

2: Make sure that Pegasus Mail is not running. Now, in the directory where Pegasus Mail
is installed, locate the file PMAIL.CFG. Delete this file.

3: Run Pegasus Mail again. It will behave as if being started for the first time. Choose
Multi-user mode, tell Pegasus Mail where to place your mailbox directories, then create
a user for yourself and login as that user.

4: Select "Help", then "About Pegasus Mail". Click the "Info" button, and find the entry
in the list called "Home mailbox location". Note this directory down on the piece of
paper you used in (1), then cancel out of the dialog and quit from Pegasus Mail immedi-
ately.

5: Copy all the files in the directory you noted down in (1) into the directory you noted
down in (4). You can use Windows Explorer or a DOS COPY command in a command
prompt session to do this.

The next time you run Pegasus Mail as the new user, it should see all the same mail files
and settings that you previously had in single-user mode. Once you are sure that the files
have been safely transferred, you can delete the contents of the directory you noted down
in (1).

Many thanks Brian.  Have I got an out of date version of the manual, mine only goes up to page 132?

The manual I quoted from is the one provided with v4.72 but the file date is 8/5/08.  Are you looking at the manual.pdf file located in the Pegasus Mail \Programs directory?