I'll take a shot at it, though if I get it right it's just a fluke. I only travel through time the way everyone else does... by watching the clock.
"Our time has past"
...but seriously if someone can travel backwards through time there are several things I would like to have changed about our "civilization".
1) Preventing genocide of all the world's indigenous populations.
2) Preventing all things related to the imperial grand strategy and all domination schemes
3) Stopping human Eugenics and plant related eugenics (Codex Alimentarius)
4) Exposing the people responsible for the Georgia Guidestones
5) and lastly stopping all crimes against humanity while preserving the true history of such crimes so they will be less likely to be repeated.
... tick tock tick tock