I can't say this emphatically enough, get away & stay away from Yahoo.
It is worth any amount of time to inform any and all People and firms that you are switching to another account(yes I know it will take a lot of time, but the security is worth it).
These are not the first two times that Yahoo accounts have been stolen or cracked.
Poor programming makes Yahoo email insecure | Computerworld
There sites are pretty to the eye, but also very prone to being hijacked, specially because they trust there Ads partners.
Yahoo ads accidentally spewed malware | Malwarebytes Press Center
Yahoo ads accidentally spewed malware - The Washington Post
Get away, quick, now.... I have told many people this for years now, but do they listen?
I'm beginning to feel like Cassandra of Troy:
Cassandra - WikipediaCassandra (Greek: Κασσάνδρα, pronounced [kas̚sŠndra͜a], also Κασάνδρα), also known as Alexandra or Kassandra, was a daughter of King Priam and of Queen Hecuba of Troy. In modern usage her name is employed as a rhetorical device to indicate someone whose accurate prophecies are not believed by those around them.
A common version of her story relates how, in an effort to seduce her, Apollo gave her the power of prophecy—but when she refused him, he spat into her mouth to inflict a curse that nobody would ever believe her prophecies.