Change Arduino internal ADC sampling frequency

I want to change the internal ADC sampling frequency of Arduino by changing some portion of the code. When I'm getting data and plotting graphs on excel, I get the freq to be 160Hz (correct me if I'm wrong)
How do I change that. Please help me. Thank you

How do I change that.

With a text editor. If you need more help than that, you'll need to show us the code that generated that result.

Changing the ADC sampling frequency will result in less precision. Is that acceptable?