Hello @CIPCO ,
At this time, images included for multiple choice style questions will always stick to a thumbnail-sized format in the survey. If a larger view is needed, they can be right-clicked, and then have the "open image in new tab" option selected.
I've marked your account as interested in being able to change the question image sizes, and submitted the case to the devs. If and when there's an update to this functionality, you'll be notified by them.
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