is it ok to paint over deck that has been sealed or better to use on wood not sealed

Better to use on new, never painted wood

No, previously applied coatings need to be removed for two very important reasons; first, stains do not adhere well to one another and second the old finish will block the new finish from penetrating the wood. If the old stain or sealant is peeling, it will pull any new coating up as well. Even if you have not recoated your deck in many years and it looks like there is no stain or sealant left on the deck, you must complete this step. Previously applied stains and sealants may be present on the deck and are not always visible and they will prevent the new topcoat from properly adhering to the wood. Strip the surface using a deck brush and deck stripper. Follow all of the instruction on the back of the deck stripper label before proceeding. Next sand the entire deck using 50 or 60 grit sand paper. This will open the pores of the wood and create a textured surface that is easier for Rust-Oleum Restore 10X Advanced to adhere to.

It can be used in that manner.

I used this 2 years ago on my deck that had been stained, but not sealed. This was a 600 sq ft deck, I used one coat, and just did another coat this month. 10x is holding up very well with no peeling or fading. I did not use the "suggested" roller as it threw 10x all over the place. I just used a regular paint roller which worked just fine.

No sealer just this paint stuff. Be careful... This does look good but it will make the boards rot out fast! It covers the boards so well it holds all the moisture in. My deck did it and somebody had me replace a bunch of boards on theirs. I would only use it on a deck that's about shot and you are just trying to get a cople more years out of it