Re-installing won't make any difference.
Some hosts have more isolated security arrangements and thus allow more direct access to their customers' files. The warning is telling you that if someone were to get past Zen Cart's security systems, they could possibly read or change those very important configuration files. Thus it's important to find a way to prevent the warning message, rather than merely suppress it.
The message is saying that the webserver, using PHP, *is* able to write to the file, according to the access check that PHP does against the file.
Sometimes, although rare, it's necessary to set these files to 400 instead of the common 444 or 644. Any lower than 400 may cause you to lose access to the file.
Some hosts have security configured such that even when you "ask" the server to set the files to 444, they remain at 644 or even get changed again later by a server security or filesystem properties check. This is why folks have asked to check and double-check what the permissions are ;)
(I've combined some of this information into the FAQ on this topic, available here:
https://www.zen-cart.com/tutorials/index.php?article=90 )




