Hi All
I 'm about to install wide board flooring, I was told to screw down the boards vs nailing. Problem...how do I fill the screw holes so they will not be seen when I finish the floor. I will be using a light color stain. Even stainable putty does not match well. Any ideas..... I wanted to use old style nails to secure the boards but seems they don't hold as well as screws.

I would avoid the screws and nail the floor with a floor nailer and also glue it.

Do not screw the floor unless you want the look of screws and plugs. As mentioned above, you can install the floor by using flooring adhesive like Sikabond T-55 and a flooring stapler.You don't have to do use a full spread of glue .You can trowel the glue in strips (aka partial spread) and then install the flooring with your stapler assuming that your boards are tongue and grooved.

Back in the day when there weren't good adhesives , screws were used to hold down wide planks .Cut nails were also used but they are no longer required except for people who desire the look of a screwed and plugged floor.

Use good urethane that comes in a caulking tube.

A bead on the ends and about every foot to 16 " across the width. Then blind nail/staple every 6-8 inches.
Don't use a slip sheet/rosin paper.

If it is over a crawl space, beware!