What It's Really like to Travel through Time: First book, "Double Trouble‪"‬

A global war veteran from the future who discovers a way to manipulate his naNabots into allowing him to travel through time somehow ends up being caught outside his own time. In order to get back what he lost without causing the universe to unravel into chaotic disarray, he once again enlists the help of an ancestor who had helped him before. But before they can begin to correct what had gone wrong, they must stay a step ahead of alternate versions of themselves who are intent on eliminating them.
Join Candace and Sam as they race through time, from the ancient Library of Alexandria to the Olympus Colony on Mars, correcting time wherever and whenever they can before their timelines are lost forever.