For Pete's sake, no! All screws are usually only slightly fastened so you'll be able to loosen them with very little effort. There's very little room for jiggling about inside the phone, so there's no benefit to using excessive force on the poor screws. On the contrary, fastening them too tightly can damage your phone!
Usually a light touch is all they need to get loose. Use the same light twist of the wrist to fasten them again. This applies to the external, as well as the internal screws.
It is very important you put the screws back exactly from where you removed them. They seem almost identical at first glance, but there are some minor yet important differences. Thanks to our magnetic project map you will always know exactly where each screw belongs.