Who makes the decision whether to settle?

You do! Your lawyer is simply acting as your agent and he cannot force you to settle your case. If your lawyer is forcing you to settle, you should find another lawyer.

A warning sign that you may need a new lawyer occurs when the lawyer asks you to pay for the costs of your trial, such as the costs of a medical expert. This is a red flag! Good lawyers will not ask you to pay for the costs of your case in advance. If they do, you should ask the lawyer why they want you to pay for the costs of the expert now, but never told that you would be responsible for the costs when you first met with him. It is very likely that your lawyer no longer wants to handle your case (probably because he could not settle it) and he wants you to accept a small settlement offer so he can move on to other cases.