over a certain length, the shown text for the URL is truncated by the system to make it easier to read, some URLs can be very long.
selecting "copy link" copies the whole URL
if you are using Firefox to read this, you should be able to simply click on the link to take you to the page.
the link i pasted in my last post was the full URL and seems to work fine here
both links you posted also work to take me to your profile page.
I don't use firefox, but cannot understand why that would return a 404 error.
this is the full URL but not as a link.
https://answers.microsoft.com/en-us/profile/ebfc2d86-c975-46d6-98c3-2f24209987a7
the red circle with "JO" appears next to your posts in this thread and in the top right corner of the page. (next to my posts you will see a dolphin
below is a picture from mine, clicking the icon in the top right of the window and selecting "my Profile" will take you to the same place as the link i posted.
on that page scroll down to see all threads that you have started, contributed to or are subscribed to, hopefully, this makes it easier to get back to a thread