You mean we can use H1 to work for the same employer after entering US with AP.
---YES, you are on H1 if working for the same employer who filed your latest H1 and can also extend H1
If I am going change employer, do I need to use EAD or I can still use H1 just by H1 transferring?
You can use EAD or can transfer H1 if on H1 status and better file H1 transfer through a good lawyer who knows all the MEMO or give him the printout of the above posted Memo