Inline Block

For those seeking the secret to this, this is what worked for me.

Go into your forms.
Select the one you need for the signup.
Go to Custom CSS and look for:

/* input wrapper (label + input) */
.mailpoet_paragraph {
line-height:20px;
margin-bottom: 20px

Then replace it with this:

/* input wrapper (label + input) */
.mailpoet_paragraph {
display:inline-block!important;
line-height:20px;
}