Hi, Zombeelina.
I had the same issue for a long time as did many other people (you can search for "complete my profile" in bug reports).
Today I fixed it by accident . Here is how you fix it:
Click on the down arrow to the right side of your forum name which is displayed in the top left corner and log out of your forum account. Then log in with the data you use to log in into the server (IG). If your forum and ingame accounts are linked to the same e-mail, the system will recognize that both belong to the same person. Now it will ask you for another password confimation, here you use your forum account password. Completion completed.
TL;DR - IG acc mail and forum acc mail have to be the same
1. Log out from the forums
2. Log into the forums with your ingame data
3. Verify by using your forum password