Cover letters

I’ve got a basic cover letter where I would edit when I apply to different jobs and stuff-

I was wondering- as my cover letter is like a letter format and my information included in the file as a header.

When I want to apply to jobs that doesn’t let me attach the cover letter as a file but rather copy and paste into the text box given on the website,

Do I copy and paste the whole thing ie including my information on the top and their address etc or it’s only the content I paste so starting from dear —- to ending with signing off my name?

If it's a text box in an application form, then just put the body of the 'letter' in the box. Don't bother with the address, date and salutation or the sign off.