Ask HN: Malicious Gmail activity on my personal account

I’ve been receiving emails about not deliverable email sent to my gmail account to TLDs within googles service, based on error they successfully sent from my actual account but it did not arrive because the account didn’t exist in that TLD.(I’ve already changed password which I already do frequently)

Can I pay for my gmail account so it’s associated with credit card? What can I do to protect? I’ve already had an account stolen from me when gmail was invite only and it impacted family members sending emails to me still on accident due to saved history on their end. I really do not want to lose this one