Password not always accepted

Hello,

whenever I try to enter my password after sleep mode or when attempting to change any system preferences, it is not accepted. However, after rebooting, I can enter it and it works, so I assume that the password itself is correct. I also tried with different keyboard layouts (since they are sometimes changed to English) or just an empty field—nothing works.

I have a MacBook Pro (Retina, 13-inch, early 2015) with OS X El Capitan (10.11.6 ) and it’s brand-new, I just got it today.

Does anybody know what’s going on here and how to fix it?

Thanks in advance for any help.

Lis 🙂