Believe an old man: everything was better in the past, sigh.
When we said "close your question" it just meant "Mark it as answered" . Today in the new community this would be ambiguous as "closing" is actually a different task than accepting an answer. But let me start like in my previous blog on that matter:
Quick answer for those who don’t want to read the whole blog:
Find your question by clicking your avatar in the menu on top right.
In the context menu click again your avatar (or alternative your name) to open your profile.
Here click Questions in the left menu if you are not directly in your questions overview. (A tip for those who do not believe that everything was better in past: if you feel that the overview does not have all your questions then please refresh the page in your browser as you might see a cached page instead of the current version)
Click the subject line of your discussion to open it.
If you got an answer that solved your issue then click "Accept answer" directly below this right answer. (Here ends the quick answer, you are done)
I marked it yellow just for this blog, in the past this was more eye catching (compare my old blog) than this grey word. If the designer had some experience with SAP's ERP system then he would know that "grey" would be associated with inactive, not clickable... but everything was clear and better in the past, you know.
In case you had more than one supporter on your question, just one answer can be accepted, but you have the option to upvote more than one helpful answer. You also have the power to downvote answers that were misleading or had a totally wrong answer.
Answered questions get this green ball in your profile. Everyone looking into your profile can see that you care about your questions, and is happy to help you with your new question.
Answered questions are also clearly visible in the overview of questions per tag.
Especially in the detail of a question a correct answer is highlighted and directly shown below the question, supposed to make it easy for future readers to directly get to the correct answer.
In my opinion such straight answers are seldom today, in many cases a discussion develops with many answers and comments towards a solution. Comments cannot be accepted as correct answer, you can just like them. Also the sequence of answers is quite disturbed with its default sorting by votes. It might be easier to identify good answers but they appear often incoherent. I can just recommend to change the sorting to oldest to follow the development of the discussion in the right sequence. This sorting might also help you to select the first answer as correct in case you got several redundant answers.
If you got no correct answer and want close this discussion, then you can actually do this from the Actions icon directly below the subject of your question.
Closing means that nobody can add a further answer to your question. You can select the reason for the closing you can also add own text as reason. Selecting "The question is answered, right answer was accepted" without having actually accepted an answer is technically possible, and is nonsense too and does not really show you in a good light.
If you got no answer and want close the discussion, then better click Delete for the sake of better search experience.
And I actually do not want to hide what an accepted answer does to your supporters.