I thought that if they do, passenger could change to another time same day with no charge

AA delayed my son's (no status) August flight by 73 mins.Also advanced his connection's departure time by 30 mins., Net effect is that he has a 1 hr connection instead of 2hrs 43 min.He was planning to meet with in-laws, can't do it now.

The first AA agent told me he could elect an earlier departure which was available. When I called a second time to do it, 2nd agent said only if the change on a single flight was >90 mins. Or if he had status

Is that the general understanding or has AA changed something else?

Call again. You'll likely find an AAgent more accomodating.

Here is the relevant section - if more than one airline involved. Look above and below the linked source.

It is important to use the correct language. First, you inquire about schedule changes and then you speak of AA delaying a flight. These are two different things. As the flight in question is not until August, it is clearly a schedule change, not a delayed flight. However, if you say "delayed flight" when communicating with the airline you risk the chance of confusing the agent - or worse coming off to the agent as one who (wrongly) can be ignored.

Likewise, don't say "same day change" as it isn't the "same day" yet. What is desired is to be re-booked at this point.

The above discussion about sticking to neutral terms unless you really mean to use the term you are using, e.g. "same day change" is important.

Equally important is to be prepared to pull the trigger when you call. If there were other options, have those researched and when there is availability, as there usually is this far in advance, grab the space on the spot.

Here, your son is not technically entitled to any sort of a free change. The length of the change, e.g. 73 minutes is not sufficient and, presuming that the MCT for his connection point is <60, he still has a legal connection.

With that said, AA tends to be accommodating. First and foremost, he should be calling, not you. It seems really weird, presuming that your son is an adult and capable of conversing.

Your son should simply say, "AA changed my schedule and I noticed that there is an earlier flight available. Because of the schedule change, would you please change me from my current flight to the earlier flight."

Indeed, Often1, what you have said is spot on. One cannot over emphasize the importance of not initiating a conversation unless one knows what one wants to ask and what one wishes to receive. In doing this, one ought balance politeness (of request) with a bit of assumptiveness (that what one wishes is both specific and something which can be done). The moment one becomes rude or demanding is the moment that one can feel assured that nothing good will happen.