I've noticed that the Acrobat window doesn't always retain its size and
position after it's closed.

After an automatic update it always reverts to a default size/position, but
there are other events which cause my preference to be discarded, such as
opening a PDF document from a web page.

Is there any way to save my desired size/position so this doesn't happen?

Can the default values be edited in the registry (for example)?

-- 
Jonathan Finney