My wife's brand new M1 Macbook Air is constantly having issues sending email.. where the Mail app keeps flashing the email window... also Preview refuses to ope

My wife's brand new M1 Macbook Air is constantly having issues sending email.. where the Mail app keeps flashing the email window... also Preview refuses to open new documents in their own window even though it is specified to do that both in Preview preferences AND the system preferences... really crappy experience.