Accepting an answer is not bounded and not final. You can unaccept an answer later if you found some new answer which is the "best answer" in your opinion. If someone is pressurizing you in comments, you can flag the comment.
From the help center:
The first thing you should do after reading someone's answer to your question is vote on the answer, like any other user (with sufficient reputation) does. Vote up answers that are helpful and well-researched, and vote down answers that are not. Other users will also vote on answers to your question.
As the author of the question, you have an additional option: accepting an answer that you believe is the best solution to your problem.
Accepting an answer is not mandatory; do not feel compelled to accept the first answer you receive. Wait until you receive an answer that answers your question well.
Accepting an answer is not meant to be a definitive and final statement indicating that the question has now been answered perfectly. It simply means that the author received an answer that worked for him or her personally. Not every user comes back to accept an answer, and of those who do, they might not change the accepted answer even if a newer, better answer comes along later.
