Also, my two IRA accounts are cash accounts and I believe they cannot be changed to margin accounts. Most of my shares are in my IRA accounts.
I had a margin account with Scottrade and when it was bought out by TDameritrade they changed it to a cash account. I opened a small margin account at TDameritrade and about two months ago they changed it to a cash account because I reside abroad now. I got burned that monday in 2012 when we all got an 80% haircut because I had purchased some calls on margin that had gone up quite a bit. Got a margin call and had to sell some stock.