Importing Demo Theme Issue

I started off with two issues when i wanted to uplaod a demo theme.
I’ve fixed one of the issues but I’m struggling to remove the other issue
“Maximum Execution Time (max_execution_time) : 30 seconds. Recommended max_execution_time should be at least 400 Seconds.”

I’ve changed the Maximum Execution Time already yet this issue stays and i can’t upload a demo theme, i’ve also tried the manual way going through Tools > Import.

Please Help me correctly upload the demo theme.