Etydhv

I am quite confused about Avengers: Endgame. If Doctor Strange was able to watch all possible future combinations of winning, why didn't Thanos use that trick in 2018 after killing 50% of the population. He could have travelled to the future, especially to 2023, and prevented the Avengers to kill 2014's Thanos.

Sounds weird but possible with the Time Stone. What are your explanations for this?

He could have travelled to the future, especially to 2023, and prevented the Avengers to kill 2014's Thanos.

He didn't know he needed to travel to the future.

As far as he's concerned, he's won. He's achieved everything he set out to do, he's destroyed half of all life in the universe and "retired" to the Garden with the Infinity Stones.

He'd have no reason to look into the future and having destroyed the Stones a couple of days later he's unconcerened with potential temporal threats since he thinks the Time Stone no longer exists.

It's also not clear whether Thanos knows that time travel is even possible, certainly there is no indication of it even being considered. Both Tony and Bruce initially said that time travel wasn't possible.

Paulie_D's answer is great and I think is the most satisfying one. I'd like to bring an additional argument to the table.

We don't know if the Time Stone is able to do that. (Or, even if it was, if Thanos is able to do the trick)

By memory (I can maybe later fact check a bit more), the Time Stone is used:

1. To forward time locally

Used by Dr. Strange in his titular movie, to rot an apple. Only the apple goes forward in time, and it anyway follows what would happen to the apple: it gets bitten, because that apple will be eaten. Unclear if the apple now has to be eaten to "fulfill its destiny".

2. To rewind time locally

Used by Dr. Strange for the aforementioned apple, and by Thanos in Infinity War to rewind Vision's "death"¹

3. To see possible futures

Used by Dr. Strange in Infinity War, to ... "live" possible futures. Not clear if he only sees them, or he has to live through them in speed 1x. I doubt, since he sees past his death, but still unclear.

4. To do the timey-loopy-thingy

Used by Dr. Strange at the end of his movie, but it's used in another dimension. Not clear if it would work in our dimension.

5. To rewind time globally

Used by Dr. Strange at the end of his movie, to rewind Earth's destruction.

So, it was never used to go forward in time if not for the case of the apple, that anyway fulfilled the destiny it was supposed to go through (in the case of Thanos, dying by the hands of Thor in 2018).
Maybe he could have been able to see the future using Strange's trick (although, it's not known how much skill is needed to pull that trick, the only thing Thanos did with the Stone is literally the first thing Strange tried "for fun"), but we definitely do not know if the Time Stone is able to make "a jump in time".