Simply remove that setting.
If you then want to set a maximum size for all images, say 640px, then add the following to wp-greet.css:
.wpg_image img {
max-width:640px;
}
Thank you yezzz! I thought I had tried remove the setting… Well I have just checked again, it depends on the theme. With default themes (2010, 2011, 2012, 2013, 2014) removing the setting results in an image scaled to wp-greet-form textarea width. With another theme I use, the setting has no effect, no scaling at all…
Welcome. If you remove the setting it will not put a width= to the html, so img then inherits the value from the theme styling if it exists, or uses browser defaults. With the above css you style it however you like.
