Hello @FBCWilm ,
The bar itself cannot be edited at this time. The social media icons are for the Share functionality, so they'll open up the social platform with a pre-built post if the person who clicks it is logged into that social platform.
Regarding the landing page form link, that links to your account's default legacy landing page form. To edit this form, go to your Sign Up Forms tab, select the Legacy Landing Pages option at the bottom, and edit the one called "Sign Up Form."
For additional info, voting, and voicing of use cases to manage this bar in emails' webpage versions, please see this Feedback thread.
"There's a multitude of ways to engage your audience through us using your social platforms - via ads, social post metrics, email links, and more! " - WillSee Article
"Target your most engaged contacts by creating a segment. Create a special offer or show your appreciation!" - CaitlinSee Article
"Greet new contacts with one or more automated Welcome Emails depending on their interests or your business goals." - NickSee Article