Looking on the internet deeply has found these results:

try my best in everything is the most popular phrase on the web.

try my best at everything 149,800 results on the web	try my best in everything 176,300 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
See, around her he doesn't have to be the best at everything. Best at Quarters, at Pong, best at everything. You're not the best at everything anymore. My mom says, "Try your best at everything you do..." If you forget everything, I will try my best to send you your recommendation letter. Because Britain is still the best at everything. We should not imagine that we are the best at everything: education in those countries is sometimes remarkable. And the English are best at everything.	I'll try my best not to intrudeon your special weekend. I try my best to realize my dream no matter how hard it is. I will try my best not to fight, Father. If you forget everything, I will try my best to send you your recommendation letter. But I promise to try my best. My mom says, "Try your best at everything you do..." I'll try my best to answer. I'll continue to try my best.

try my best at everything

149,800 results on the web

try my best in everything

176,300 results on the web

More popular!

See, around her he doesn't have to be the best at everything.
Best at Quarters, at Pong, best at everything.
You're not the best at everything anymore.
My mom says, "Try your best at everything you do..."
If you forget everything, I will try my best to send you your recommendation letter.
Because Britain is still the best at everything.
We should not imagine that we are the best at everything: education in those countries is sometimes remarkable.
And the English are best at everything.

I'll try my best not to intrudeon your special weekend.
I try my best to realize my dream no matter how hard it is.
I will try my best not to fight, Father.
If you forget everything, I will try my best to send you your recommendation letter.
But I promise to try my best.
My mom says, "Try your best at everything you do..."
I'll try my best to answer.
I'll continue to try my best.