QWin: SEC_1 - Old Problem, haven't seen any solution - help

unknown

Several Accounts (Stocks, single Mutual Funds) have had some or all of their security names changed to SEC_1 (maybe failed validation(s) or migrations for version 'upgrades' over the years). When I edit the transaction, the security name is grayed-out. When I go into holdings, select SEC_1, and click 'Edit Security Details', I can change the name there, but it is changes in all affected accounts. 
How do I Get the correct security name in each affected account?

unknown

When I go into holdings, select SEC_1, and click 'Edit Security
Details', I can change the name there, but it is changes in all affected
accounts.

What else do you expect?
SEC_1 is the same security in all the accounts it is used in.   You can't change the name in just one account.

As for not being able to change the security in a given transactions.  By any chance is that account set to a "Single mutual fund account"?

If so you can't change it because the account can only hold the one security.