If QB is creating accounts it is because you have created items and not defined a COG account for it (in item setup details) - then QB posts to a default location that it created. Open the transactions that may appear in that default account - then backtrack the transactions to the items involved and correct the settings for those items.
Remember that in QB 'items' link to accounts - not the other way. and items 'must' link to accounts so if the account is missing (or invalid) then QB puts an account in for you.
Renaming or renumber that account wont change anything - the problem is in the ITEMS
There are NO items and no transactions that use 50001. When the integrator (The Wren Group, that we paid WAY too much money to set up our QB file) set it up, they didn't let QB create a default COGS account for the items.
So now, when we set up a new item, it defaults to 50001, which is what QB created as COGS, and we have to select 50000 for EVERY ITEM WE CREATE, EVERY TIME.
At some point, we will fail to change it to 50000, and it will hurt us.