Setting options programatically

Hi.
I tried making default settings before actually installing the plugin (mainly just the message text). It is a serialized array in wp_options cookie_notice_options, the specific field is message_text. So far so good. But when I install the plugin afterwards it seems to overwrite the field. I even tried to just copy the whole option_value of cookie_notice_options, still gets overwritten. However, after updating or reinstalling the plugin, the options are retained.

I’m not sure how this is done, so… any tipps? 🙂

Cheers
Floutsch