How do I mark an issue/question as solved?

Solution
You click the green button in the post labeled "Pick as the solution"

But since you can't choose your own post as a solution, I just did it for you.

Michael_265

Commendable
Apr 22, 2016
19
0
1,520

Here's another one.
http://www.tomshardware.com/answers/id-3554728/toshiba-flash-card-problem.html

In neither 'issue' have I ever seen the 'green button' for any of the comments/answers by others.

Any idea why? Do I possibly not have sufficient privileges?

ETA
I am beginning to suspect you mean a 'green button' in the EMAIL I received -- not in the comments section.
Correct?

 
Members can't nominate their own posts as the "Best solution" for a very good reason.

We have a ranking system/leader board based on how many "Best answers" a member gets each month.

It wouldn't be fair if you were able to boost your own ranking just by a simple mouse click on your answers.