You don’t have any complete sentences, and 3 + 4 are very incomplete. That makes your question difficult to answer.
Here are some comments:
1)So at that age, AS we try to learn from different people and about different places,… --> OK – ‘as’ refers to a period of time gradually/progressively.
2)So at that age, WHEN we try to learn from different people and about different places,… --> OK – ‘when’ refers to a period of time as a whole.
AS I was young,… This could mean “Because I was young”
WHEN we are(were?) young,… OK. The choice of tense depends on whether you are talking about the past (were) or talking generally about all of us and what always happens when people are young.