Changing settings memory_limit/post/upload size + execution time

For my new Wordpress site I needs the following settings.

memory_limit 256 MB
post_max_size: 64MB
upload_max_filesize 64MB
Max. Execution Time to 300s

Currently i’m at 158MB for memory_limit and 20MB for max_post_size and 20 execution time. Can anybody know and point me where and how thiscan be adjusted?

I don’t think anyone can point you to it, because you cannot change those settings. The limits as they are right now are enough for most sites. If your site truly needs so much memory and such a large upload size, I’m afraid your website is just too big for free hosting.