In terms of layering, where do I put a memory foam pad on the bed?

Do I put it over the sheets? Right over the mattress? Over the mattress pad?In terms of layering, where do I put a memory foam pad on the bed?
Here is the order: #1. The mattress pad (I use two) then the foam pad and then the sheet. If the foam pad does not have its own cover (some do and some don't). #2. The mattress pad, the foam pad, another mattress pad and then the sheet. If no cover on it, its needs to be sandwiched between regular pads.In terms of layering, where do I put a memory foam pad on the bed?
My setup is mattress, mattress pad, memory foam, and then bottom sheet. Having it right below the sheet gives the best support and is most form fitting.
I would put it over the mattress but under the sheets. However you prefer.