Cost basis for security, not showing, how to correct.

unknown

I have securities where the Cost Basis does not show, there are NO placeholder entries for them AND there is a transaction in the register for when they were BOUGHT with the cost and that shows money was taken out of the account to cover their cost. The security names are unchanged and are as shown on the Brokerage account I download info from. HOWEVER, the Brokerage changed my account numbers, so there are deletions of shares (shares REMOVED) from the old account and then addition of shares (SHARES ADDED) in the new account. This appears to have lost the COST BASIS connection. IRA account lost the Cost Basis, non-IRA account maintained the Cost Basis.
How do I edit/correct cost basis for  these securities?

q_lurker

One step at a time.  If your brokerage changed an account number, you generally have two option in Quicken:

1) You can disable your current account in Quicken from online access and then reconnect it to the new account.  This may generate redundant or unnecessary transactions on the first download into that account, but cost basis info and history are most cleanly kept.  

2) You can create a new account in Quicken to be matched to the new account at the brokerage.  In taking that route, you should create the account in Quicken and use the Shares Transferred between Account macrotransaction to move holdings from the prior Quicken account to the new Quicken account.  After that is done, then you can cleanly associate that account to the brokerage account.  In that approach, your prior history of buys, sells, dividends, etc. remain in the original account, but the cost basis of the current holdings, lot by lot, gets transferred to the new account.

I suspect your downloaded transactions for the new account in Quicken uses one Add Shares transaction per security.  I would try the following based on what I think is in your account now (and assuming you want the new-account solution):

a)  Backup your data file so that you have a solid recovery point.
b)  If your old Quicken account has a series of "Remove Shares" at the end, delete those transactions so that the account currently ends will all the holdings that should have been moved to the new account.  
c)  In the new account, delete all the Add Shares transactions that came from the brokerage download.
d)  From the old account, use the Shares Transferred transaction to move all shares of all securities to the new account.
Review the results.

If any "cash" transferred, that needs to be a separate process (not covered by Shares Transferred) but is likely OK from the the downloading process.