Newsletter form customization and weird message

Hello,

I was working on the site and received this message:

'You need a higher level of permission.

Sorry, you are not allowed to customize this site.'

Then I was logged out and after I logged in again, I noticed some changes on the website.

One of them is this one:

• the Subscribe button from the Mailchimp newsletter changed font. It was Lora and now it's something else. Also, when I hover over, instead of white, it appears black.

Could you help me change the font and color of the button back?

Also, do you have any idea why I received that message? I am the administrator of the site.

Thank you,