Ruby, you say she always smiled and said hi; HOWEVER, you were given instructions to stop the behavior and a chance to change your behavior, before you were ever fired, and you CHOOSE to disobey those instructions.

You did not become crazy since March because of what happened at the fast food joint. You exhibited the same disobedient, unprofessional behavior at both jobs. The fact that your boss at the Sam's Club job said you were acting better is moot, since you yourself said you broke a lot of rules, they just didn't know.

So you've got a new job now. That's great. Learn from the mistakes you have made at Sam's and the fast food joint and just obey the rules. In all of these jobs, the reason you ended up getting fired was your failure to follow rules or instructions. You were told to stop coming in when you weren't scheduled at the fast food job, and you continued to do so, so you got fired. You were told not to swear on the sales floor at Sam's, you did anyways, you were suspended, possibly fired. If you obey all the rules, you should be fine. If you make a mistake and are given a warning, then obey the warning, and you should be fine. It is not rocket science to follow rules.