There's a difference in other cases: Example 1: I've been thinking about it: Estive pensando sobre isso = correct use. Fui pensando sobre isso = wrong use (unless you mean you were going somewhere and along the way you thought about it). To Be = Ser ou Estar, u know, but in Portuguese, "ser" means a definitive state meanwhile "estar" means a transitory state. Example 2: Ela é irritada. (She's a angry person). Ela está irritada. (She's is angry at the time) Sorry if I don't write very well, I'm learning.

Grammatically speaking, "fui" is the Pretérito Perfeito do Indicativo for verb "IR" (go) and "estive" is the Pretérito Perfeito do Indicativo for verb "ESTAR" (to be). Eu fui aos Estados Unidos ano passado. = I went to US last year. (IR) Eu fui aos Estados Unidos. = I've been to US. I've never been to US. = Eu nunca fui aos Estados Unidos/Eu nunca estive nos Estados Unidos. (IR/ ESTAR) The problem here is not the Portuguese, but the English: you have to form the sentence according to the time (simple past or present perfect).

Obrigado! Thanks for you help! I appreciate.

Eu fui à praia - I went to the beach Eu estive na praia - I was at the beach

Hi :D Pretérito perfeito: Estive em Portugal. -> I have been in Portugal A Joana foi feliz. -> Once Joana was happy A Joana esteve feliz. -> This statement is not usual, we use to say "Joana era feliz", instead Joana esteve presa. -> Joana was imprisioned during some time. Pretérito imperfeito: Estava em Portugal. ->It applies to something that ocurred during a given time period or with some concomitant event. A Joana era feliz. -> Joana was happy during given time period in her life, until something happened, maybe. A Joana estava feliz. -> In that moment Joana was happy I hope had help u :)