Thank you for the fast reply from my last thread
Cloudflare SSL is not working on my site
I also contacted their support group and they said,
We are seeing delays with our SSL certificate provider
So they reordered my certificate and is now active.
Right after, I followed @NGiNX reply of the steps
to change my Wordpress default website address
I got some infinite redirect issues on that, but fixed
by installing a plugin: CloudFlare Flexible SSL 
But sadly, I have another problem.
Everytime I go to https://3db7.xyz/wp-login.php,
entered the correct username & password, then
after clicking the Log In button > 400 error shows up.
Can you try logging in with a non-https connection?
Have you installed any WordPress plug-in so far?
Please try accessing your website using http, yes please turn off the cloudflare orange cloud.
I can log in if I set to DNS only on Cloudflare’s settings
Just one plugin, CloudFlare Flexible SSL
Yes I successfully can logged in on http
Then it mostly is a .htaccess problem I will fix that for you.
Oh no it’s not the problem.
Can you modify your website URL in the database and set it with https?
Done. It’s now with https
Can you try logging in now with https
Please clear your browser cache and try again
Oh I just found the problem, its with the browser I’m using. 
Even though I completely clear all its data, cache, cookies,
and going through incognito/private mode, I still got the error,
but on a different browser, it works smoothly. 
Maybe I need to uninstall and do again
a clean installation on the browser.
Thanks again for helping me out! 
