We no longer pin the accepted answer (with the green checkmark) to the top of the list of answers. By default, we now sort strictly by votes (descending order by highest score), and the accepted answer's order in the list is based on its score.
and it is asked on Meta Stack Exchange if we would like to have the accepted answer unpinned on our site:
We can change the way the engine sorts answers in site settings. We would like to hear from you all if it is something you want to see on your site. ... We are going to collect feedback before the end of September 19th.
If Joomla Stack Exchange is going to unpin accepted answers, we must gather indications of support on this Meta page. Please voice and vote your opinion concerning what is best for our community.