I have now acquired several citrus and have them in containers. I use a very fast draining mix because of our summer rains in So. Florida. I understand the ideal PH for citrus is lower. My trees are new, growing and doing well. Should I lower the PH? How?

Do you know what rootstock they are on?

4 are on Flying Dragon
4 in something with the initials KH

You can lower it to around 6.5, but at 6.9 I wouldn't bother to worry about it. - Millet

How accurate is your pH measuring method ?
Are your trees showing any signs of nutrient deficiency?
The main reason for monitoring pH is to control micronutrient availability.
ie you apply fertilizer, but plant cant take it up due to pH.
If you are not seeing any deficiency problems. and plants respond well to fertilizer, should be no need to alter pH.

I think my PH meter is a pro grade and accurate
The Meyers lemon is showing some off coloring the other 6-7 are fine
By the way what kind of root stock is KH?