[Evolution] Html or text response question

["theapplepie differentmail com" <theapplepie differentmail com>]

Hey guys

After upgrading to Ubuntu 16.04 and using Evolution 3.18.5.2, the
program would ask me upon replying/"edit as new email" to a html-email
whether I want to continue with a html or text-email (at least that is
what I remember). After answering the questions a few times, I clicked
on the option "save preference" (or similar). Since then it does not
ask me anymore ;-) but I did not find any option in the preferences or
dconf-editor to let me ask again or at least temporarily change to the
initial setting of asking each time. Is there an option to change this?
And if yes, how?
I want to go back to the initial behaviour (permanent or temporary) as
I have a small problem: When I "edit as new email" a sent html-email,
it would open as plain text email and when I switch from "plain text"
to html the background picture of the original email has disappeared
(and needs to be added again). I can only work around this when I set
"Format messages in HTML" in the Composer Preferences although I
usually prefer plain text emails and this was not needed in previous
Evolution-versions.

Thanks for any help in advance

Dan