‘I’m Not Fussed’ Means ‘Either Is Fine’

When several options are acceptable, Australians often say, ‘I’m not fussed.’ It means ‘I don’t have a strong preference’ or ‘either is fine’, not ‘I feel no anxiety at all’. For example: ‘Tea or coffee?’ ‘I’m not fussed — whatever’s easiest.’

It is usually softer than ‘I don’t care’, which can sound as though the matter is unimportant to you. Still, ‘not fussed’ does not express enthusiastic approval; it simply leaves the choice to the other person. Americans will understand it, but are more likely in everyday speech to say ‘Either is fine’ or ‘I don’t mind.’

https://dictionary.cambridge.org/dictionary/english/i-m-not-fussy-fussed
https://www.collinsdictionary.com/dictionary/english/fussed
https://www.abc.net.au/news/2010-10-06/cahill-in-doubt-for-paraguay/2287964