How does the personal URL work?

So, we recently surpassed 100 subscribers on our channel and created our personal URL. When I write down the URL on my Computer, it works just fine, but we have 2 problems, and I would like to ask you guys for help!

At first, when we enter our channel by searching it on Youtube or otherwise (actually anything but entering the personal URL), it doesn't show our personal URL but the old one (the one made of random letters and numbers).

And the second problem is, when we enter the URL on our mobile phones, it doesn't load our channel at all, it just doesn't work.

Do you guys have any idea how to fix these two problems? Thank you in advance!