I’m not able to download or update my apps as it says the previous owners iCloud account but the phone is logged into my iCloud account

What account is logged into Settings > iTunes & App Store ? The account that you are logged into for iCloud is the account that your backups will done to, the account that is used for downloading new content from the store is the account logged into the store.

If the previous owner didn't reset the phone back to factory defaults prior to selling it to you you should do so (Settings > General > Reset > Erase All Content & Settings), anything downloaded by his account is permanently tied to his account.