Time only seems to go slower in space than it does here on earth because things are moving much slower in space than things do here on earth.
On earth everything is sped up and we are constantly moving around going places and getting things done so it seems like time is going much faster here on earth than it does in space.
When you're in space everything you do or everything around you is moving slow due to less gravity and friction in space.
So when in space time seems to slow to a crawl while here on earth it seems like time is running and not slowing down.
But actually no matter where you are whether you're in space or here on earth the time goes at the same exact speed.
When you move fast and are having fun time goes fast or seems to go fast but when you're not moving fast then time seems to slow to a crawl.
It's just our perception of time.