Hi,
1) To remove the author and date follow the steps below
Go to Dashboard >> Appearance >> Customize >> Theme settings >> Single Post Page
Refer screenshot https://ibb.co/6DrBBXP
2) You need to add an embedded video link of the youtube video.
3) To remove the footer credit link follow the steps below
Go to Dashboard >> Appearance >> Customize >> Additional CSS >> Paste the given CSS on it>> Publish.
span.credit_link {
display: none;
}
4) Add the following CSS to change the color of the contact form message color. Follow the steps below to add CSS
Go to Dashboard >> Appearance >> Customize >> Additional CSS >> Paste the given CSS on it>> Publish.
.wpcf7 form.sent .wpcf7-response-output {
border-color: #46b450;
color: #46b450;
}
Many Thanks