What males a FA a fiduciary or not. Is there a different license or certification or is it something they decide on their own?
Good question. Let me try to give a brief answer from a customer's point of view in an investment context:
1) In the investment world, the basic license is a Series 7, which is the sales rep (aka "registered representative") license. One of the responsibilities of a fiduciary is "loyalty" to his customer. A rep's loyalty is to his employer. His legal standard for products is "suitability" for the customer. So if he has two mutual funds that are otherwise equivalent, but one pays big sales commissions, he will sell the latter.
A legal fiduciary (Registered Investment Advisor) will have either a Series 65 or a Series 66 license.
There is also a kind of odd duck, a Series 7 broker working for an investment advisor: "Investment Advisor Representative." As I understand the idea, this guy sort of inherits a fiduciary responsibility from his employer. I am not as comfortable with this, though I am involved with an IAR through a nonprofit I work with and she is a solid citizen.
Another odd duck is the CFP, "Certified Financial Planner." I think that holding a CFP is probably A Good Thing, but despite some advertising you may see, holding a CFP does not make the person a fiduciary. It is more like the Good Housekeeping Seal of Approval: a designation bestowed by a business, having no legal teeth.
If you go to
https://brokercheck.finra.org/ you can check any brokers credentials. And you should.
2) This is actually more important: A fiduciary is someone you can trust. Credentials aside, you need to do a smell test. Brokercheck will show you any customer disputes or disciplinary actions. These are big red flags. Brokercheck will also tell you how long the person has been licensed and who they have worked for. Unless you want to trust your money to a trainee, I would look for lots of experience at respected firms.
In theory, someone could assume fiduciary duty to you by simply signing a civil contract. But without FINRA backing, you would have to go to the civil court system for any redress. No fun and not cheap.
Finally, just to muddy the water further, the Department of Labor's "fiduciary rule" says that any advisor involved with retirement investments must act as a fiduciary -- even the Series 7 guys. BUT if you have non-retirement accounts with the same person, he/she is not held to a fiduciary standard for those. Further, IMO tigers aren't going to change their stripes just because of the DOL rule, so I would still avoid the Series 7 people just on general principles.
Here is a view from inside the industry:
https://www.kitces.com/blog/the-4-different-types-of-financial-advisor-fiduciaries/