Quicken doubling my Fidelity retirement accounts

Switching back to Complete might not fix the problem without a bit of fixing.

First off it is known problem with Fidelity/Retirement accounts/Simple that it doubles the value by adding in a cash value that should be zero but is set to the full value of the account.

The way the Simple investing mode works is by looking at the "summary information" and putting in add/balance adjustments to get what Quicken has to agree with the summary information that was sent with the downloaded transactions.

The Complete mode on the other hand works by only using the downloaded transactions.

When you switch from Simple to Complete Quicken isn't going to magically know what transactions to change to get it back to the proper balances.

Since the only problem is that you have a cash balance when you shouldn't, look for a transaction that adds cash to the balance in the amount equal to the value of the account and delete it. That should bring the account back to what it should be since the security entries are correct.

But there is a warning here, while downloading transactions in Simple mode it has not been trying to track the buys and sell to keep track of the actual cost basis and such. Whereas an Add Shares might the right amount of shares, it won't have the right cost basis. So, if you see that the transactions aren't buys/sells and you just started using Simple mode the better corrective action might be to restore from a backup before you switched to Simple and go from there.

If these are brand newly added accounts, you can delete them and re-add them, but use Complete not Simple investing when setting them up.

The problem isn't resolved!

As I said Complete mode uses the transactions from the download, this is what has been used for decades and as such much more likely to be correct. The "Summary" information has always been sent with the downloaded transactions but Quicken hasn't ever been reconciling/using the cash balance. The Simple investing mode is new, maybe a year old, and it uses that Summary information (shares and cash balance).

Fidelity has that cash balance wrong for their 401K accounts (not their brokerage of IRA accounts).

If you went back to Simple mode, the next time you did a One Step Update Quicken would read that same incorrect cash balance and you would have the doubling again.