I can not change the mail address of my account, what is the reason?

You can usually change the e-mail address of your account yourself and thus transfer the account to another e-mail address. To do this, go to "My Account" in your account in the upper right drop-down menu. There, please select the section "Email/ Account transfer" and click on "change".

If you don't see a change button there, your account is a sub-user account. In this case, changes can be made only by the account administrator. So to change your email address please get in touch with the admin of the account. This person can change employee accounts, i.e. change and transfer e-mail addresses.