When I answer a new card, everything is alright with the scheduling. Houwever, when it comes to its first review, there are some issues. The hard button is fine (I need to review that again in 2 days), but the good button shows that I need to review it only in 7 days. I’ve never done something to change it or so, but i don’t know how to fix it. I’d like to remain with the good old button to review the card in 3 days. If it is not clear bc my poor english, pls tell me. thanks
Welcome to the forum. I am an Anki user like you.
FYI. there is Anki Manual. Study the section “Deck options”. Make a test deck and a new Options group - to see how Anki changes Intervals in real time.
Also, get the add-on “Deck and card info sidebar…”; it will show you much more info you must learn what that weans and how to use it to change intervals.
PS. To memorize this info, there is a great software called Anki :
https://docs.ankiweb.net/#/ 
Just make cards for that section of the Manual. And review them more often than Anki defaults suggest; change the Interval Modifier to 80 or 60; learning / relearning steps to 5 10 20 ( as a start ). There are no stupid questions - at the beginning
thanks, i’ll try it!!