How to take ROTH earnings out , after age 59.5, if you have multiple conversions some more than 5 yrs old others less than

If I did an IRA to ROTH conversion that is now 5 years old, and I did another that is 2 years old, even if I am over 59.5 I believe I must wait to take out earnings, from the conversion that is only 2 years old, tax and penalty free but from the IRA conversion that is 5 years old I should be able to take out earnings without tax and penalties. Is that correct? I am only talking about conversions here. The desire is to withdraw an amount that exceeds all the conversion amounts so I have to take out some earnings. How would the IRS know that the contributions taken come from the first conversion? Do I have to create separate IRA accounts for every conversion?