Hello desired alias!
You should be able to access your iTunes & App Store settings on your iPhone. We'll do all we can to help.
Just to confirm, are you following the steps as outlined in the article below? Depending on your iOS version automatic downloads will be located in Settings > iTunes & App Store or Settings > App Store. Update apps or use automatic downloads
If you're still having trouble do you know if there are any profiles or restrictions enabled on your device? If so this could be the reason why you're unable to enable automatic downloads.
Use parental controls on your child's iPhone, iPad, and iPod touch
Install or remove configuration profiles on iPhone
If you do not have any restrictions or profiles configured we would recommend that you check for an iOS update available. Please make sure that you create a backup before updating.
Update your iPhone, iPad, or iPod touch
Keep us updated.
Cheers!