Ok, so, tried to change to PHP version 5.6.20, and after downloading was finished it stayed at provisioning for approximately 12 hours, before I decided that it was never going to stop provisioning. I shutdown the local by flywheel app and restarted it, but the site no longer works. When I go into the SSH terminal for that site, there are no folders at all in the /opt/php directory, so it seems that it never even installed PHP 5.6.20, however, it shows it as being installed in the local by flywheel app, since I no longer have the option to download it, just to switch to it.
But, it doesn’t matter what PHP version I use for that site now, whether it is 7.0.3 or 5.6.20, neither of these versions work since the php directory is completely empty for this site, and unable to download it anymore. When going to the site, it would give me 503 error. So, now I have completely deleted the site so that I am going to start fresh and try again, however, I fear that I will not be able to get PHP 5.6.20 working on that site, since the app thinks it’s already installed. We’ll see what happens I guess… I made a backup of the files before deleting the site.
I just wanted you all to know this. BTW, running Apache if it matters.
UPDATE
Trying to create a new site just now with the same name as the other site had, after deleting other site, and selected PHP 5.6.20 with apache, and it seems that it is unable to create the new site as it is stuck on Provisioning PHP and doesn’t seem to want to finish on that process of the site creation. What to do now?
NOTE
The only reason I downgraded from PHP 7.0.3 to 5.6.20 was because I need to use ImageMagick extension for PHP, and you folks do not provide this extension for PHP 7.0.3 (as you should, or atleast provide the php7.0-dev package in apt-cache search . so that I can build the imagick.so extension using phpize to prepare it, once downloaded). I have had PHP 7 with imagick extension working fine on localhost, so I’m not sure why you folks do not include this extension, or provide a means to have it running with PHP 7.0.3. In any case I need ImageMagick extension for PHP, so that is why I need to change to PHP 5.6.20, in order to get it working on the site 
UPDATE
Was able to create a site using nginx with PHP Version 5.6.20, and was able to install the ImageMagick extension just fine on that site. Guess I’ll just create sites with nginx now. Not sure on the differences between apache vs. nginx, but I guess nginx is overall better from what I hear. But seems that my apache install is corrupted somehow.