Hi Sakar,
My Domain host modified them first (there was an issue on their end) up to those values & then I have increased them further at their recommendation when I contacted them – to no avail.
Forgive me, I am not very familiar with website maintenance, having moved from Moonfruit, and particularly not with cPanel in general.
How would I use echo phpinfo(); to verify it has worked?
Update: I have increased the max execution time to 1200 seconds and still got the http error with a larger image (but smaller images are still fine).