"If I were rich" is proper subjunctive mood. "If I were rich, I would travel around the world."

If I was/were rich ... are identical in meaning. They are 2nd conditional. The 'correct' form is the subjunctive 'were.' However, so many people use the past simple 'was' that it is considered acceptable now. BUT I WOULD USE THE SUBJUNCTIVE IF YOU TAKING AN EXAM. It's a safer choice. It is the 'correct' form. When I was a girl it was considered very wrong to use 'was.' Times have changed, and it is not considered so wrong now.

Sería If I was Rich, porque estás hablando de Primera Persona Singular, y usas Was para los singulares de Primera y tercera persona

were because it's unreal condition

He, She, It are singular and uses was. I, you, and We are plural and uses were in the past tense.