See below for a shopping list and tools subscribe to this old house.
Plywood floor squeaky in my new house.
This causes the floorboards to rub against each other or against the subfloor or against the nail casings.
If the underside is covered you will have to work from above.
If the tops of the floor joist are not flat and level then the sheets of plywood or sub flooring will not be fully supported evenly.
Since day 0 one of the major issue had been my flooring both main level and the upper level.
Which is all carpeted.
Floor joist tops not level.
With hardwood floors drive ring shank or cement coated flooring nails into the seams between boards.
Squeaks happen when a house settles and wood flooring dries and then expands.
Nails rub on plywood when walking on floor and cause the squeak.
Over time the portions of the floor that have been sucked down will try to go back to a flat and level position.
For squeaky floor repair begin from underneath the floor if you can.
Separate wooden bridging members to eliminate noise problems.
I have some squeaks in my floor that i have narrowed down to exposed nails coming through the plywood sub floor from the basement which is not finished.
When nailed down the sub flooring will be sucked down unevenly.
I have posted the video below of the upper level.
This old house general contractor tom silva silences some squeaky floors.
Before i attempt to try anything i thought i would see what you suggested.