does she remeber?

I am 11 and i have a bipolar friend who does not know i know she is bipolar. i have put out two posts before this.  my friend  has gotten quite mad at me a few times and has said some things to me that are very upsetting. My question is when she is in an episode and gets mad does she remember it afterwords? becasue both times when i talk to her about it after she always tells me that she would never say anything like it when infact she has. Also are there any warning signs that a person is entering mainia or depresion? i am trying to learn as much as i can about bipolar  so i can help my friend. thanks for any info! =)