Hey, Andres, how are you doing?
Allow me to enlighten you upon the usage of ''would'' in the contexts concerned:
1) Firstly, you should know that ''Would'' is a modal. It is used in a number of different ways. However, when the situation entails facts about the past, you can use ''would'' to talk about something that happened regularly in the past but no longer happens.
E.g.: ''We would normally spend the winter in Miami.''
E.g.: ''I would often visit my grandmother at weekends.''
2) ''Used to'' is an idiom that has a similar meaning.
E.g.: ''She used to visit them every Sunday.''
E.g.: ''In the afternoons, I used to read.''
HOWEVER, the idiom ''used to'' can also be used to talk about states and situations that existed in the past but no longer exist. You can say, for example, ''She used to work there''. Though many people may use ''would'' and ''used to'' interchangeably in this case, I would recommend that you not use ''would'' (as in ''She would work there'') in order to convey the aforesaid sense that is grammaticaly restricted to ''used to''.
3) When the negative form of ''would'', which is ''would not'', is used to talk about something that happened in the past, it means that someone refused to do something.
E.g.: ''They just would not believe what we told them.''
E.g.: ''I asked him to come with me, but he wouldn't.''
I hope you have understood it!
Should you have any further questions concerning English grammar, do not hesitate to contact me. I should be pleased to help.