But most time it’s quite suspicious for an account to change email we never can tell if the account was hacked and the culprit wants to change email. So many people would have different views on the situation.
OP, note that while this might be true, 1) it probably shouldn't be suspicious, since changing e-mail addresses/passwords can often be done for mundane reasons like security or changing e-mail providers, and 2) it's way more suspicious when someone wakes up after a long period of inactivity and changes both their e-mail and password. It doesn't look like you've come back from a long break, plus you've asked for help in this thread so I don't think anyone is going to give you a hard time because of an e-mail change.
But you can prove account ownership with password, signed message from your Bitcoin address. Did you sign any Bitcoin message with your address on Bitcointalk?
That's a good point, and I'd definitely suggest OP stake an address if he hasn't already. You never know when you're going to have to prove you own your account, and you don't want to make it to Hero or Legendary rank only to have some situation occur where everyone is asking you to sign a message only to realize that you never staked an address you can sign a message from. I've seen that happen before.
Publicly announcing the change of email address (before the change itself) might be a good idea so that you can always refer to that post if someone ever asks you about it (for instance, changing email is sometimes associated with account sale or even hacking).
I'm not sure it's necessary (or even a good idea) to do so, but I remember doing exactly that in the past, although it might have been my password and not e-mail. I just wanted to head off any suspicions at the pass, because I know there are members of the community who notice these things all the time, and I didn't want anyone to think I got hacked.