There still seems to be some confusion about terminology. That is making it hard to help.
>>SORRY, I thought you had switched from Verizon to Cox. I misread that.<<<
"Cox" is an ISP, not a webmail service. ISPs offer email accounts that can be accessed via an installed email client, such as Outlook, and (in many cases) via a web interface, via the internet. For example: "username123@Cox.net"
"Verizon" is an ISP, not a webmail service. As an ISP, they would offer ISP email accounts to their customers, just like Cox. For example: "email@example.com"
AFAIK ISPs do not provide webmail service. They provide ISP email accounts. And some of them provide access to those ISP accounts via a webmail site.
For example, I can access my ISP account "firstname.lastname@example.org" either from my email client (Thunderbird), or by logging in at "webmail.ny.rr.com"
"Yahoo mail", like gmail, is a webmail service. You would have an email address such as "email@example.com". You ought to be able to access this account 2 ways: directly from an internet browser at mail.yahoo.com; and from your installed email client (when you set up the account in Outlook). Unless you route your messages through your ISP, you ought to be able to use the standard yahoo mail server settings in Outlook for both sending and receiving.
Outlook is an email client. It can be set up to handle both ISP mail accounts and webmail accounts, such as yahoo! mail.
I'm sorry, but we seem to be going around in circles.
Support is a two-way endeavor.
We are not in front of your computer.
Without answers to the basic questions I asked, I don't think I can help much.
I understand that you are tired and frustrated -- computer issues (especially with email) can be very confusing and challenging.
I suggest that you please wait for someone else to assist you here -- there's bound to be someone who uses Verizon for their ISP, Outlook for their email client and yahoo for their webmail.
They will be able to better assist you.
Or perhaps try contacting VERIZON. Whether Cox or Verizon or Comcast or Spectrum or Charter, your ISP ought to be able to provide robust support to their Business customers (that's why you pay them all that $$):