i work for a big group and on the version of limesurvey i use i can't manage themes even in administrator mode
Then your only chance is to get in touch with the person that is responsible for the Limesurvey installation in your big corporation and relate the bug in the theme. There is not much we can help you with, as this a custom theme and you have no rights to change it.
And while you are at it, you should inform this person that the installation is over 5 years (!!!!) old and thus hasn't received any update or bug/security fix since then. Especially in times of GDPR this is a fairly risky move, as you are supposed to use 'state of the art' software to protect data.
I think it will be hard to argue that your company uses 'state of the art' software with a 5 year old software open to the internet (and there have been 2 major stable versions of Limesurvey since then).
So I would highly recommend to make a switch to LS 3.x (not to LS 4.x yet, as it is not yet considered stable).