Did you try the Next/Previous or Previous/next without closing the form?

You should be able to find some Recordset VBA on this forum, if not I have some very simple examples, but I do not think it will help. The record that you are on has to be saved by Access before you can get to the data, another alternative may be to store it in a variable (may be set to "Public") to be picked later.
Further alternatives are, use an update query after the records have been changed or save the data to a "Dummy" table and pick it up from there to update your Memo field.
If you can post an example I could look at it for you.