one day versus some day

[JarekSteliga]

Can you please help me out with this?
Am I right in thinking that while both 'one day' and 'some day' can refer to the future, only 'one day' can refer to the past? Here are some examples to better show what I am on about:
'I intend to become an astronout one / some day'
'I was one day day walking along the beach'
but not
'I was some day walking along the beach'

[J&K Tutoring]

You are correct, though it would be more common to say, 'One day, I was walking along the beach'

[JarekSteliga]

You are correct, though it would be more common to say, 'One day, I was walking along the beach'

Thank you