求助炒股报税

求教大家一个问题，描述如下：

本人在国内开了TD Ameritrade的账号炒美股，那时填的是国内地址。

现在到了美国了，J1身份。以前也在美国呆过1年多，应该超过183天了。

请问这种情况，
（1）需要跟TD Ameritrade更新新的地址信息吗？
（2）如果用之前的账号炒股，股票收入还需要向IRS报税吗？
（3）目前J1身份是有中美免税协议，tax treaty的，炒股收入可以exempt吗？

TD公司的个人中心，说information change了，需要update I-W8BEN表，请问我现在算是resident of U.S.吗？
我以前肯定是non-citizen和non-resident的。
TD的个人中心有这么一个页面：
Is it time to update your W-8BEN?
Complete a W-8BEN if:
You received a message in the secure Message Center saying that your form is due
Your form has expired
Your information has changed

You must provide a new IRS Form W8-BEN every three years or sooner if your information changes. If we don't have a current W-8BEN on file for your account, you'll be subject to trading restrictions and backup withholding. Joint account owners should complete a paper W-8BEN, available at Client Services > Forms & Agreements.
The IRS requires that you fill out this form using English characters only.
请大家指点一下，多谢多谢！