Additional security tips once you have successfully set up account 2 as the primary alias.
1. Please stop using SMS as a 2FA verification method because SIM card swap attacks are a common threat nowadays. This is a telco industry well-known vulnerability that hackers take advantage of. In the following article, I mentioned the danger of SIM card swap attacks, you can see a man lost his saving because of 2 SIM card swap attacks. https://answers.microsoft.com/en-us/msteams/for...
2. I understand some banks still require SMS for 2FA, I suggest please buy another phone number only for bank SMS verification purposes. Do not ever, (I repeat once again, do not ever!) under any circumstances registering this new phone number to any account other than your bank account. Don't even use this phone number for your email account. Only you know that the phone number is for bank verification purposes, other people/party has no business knowing the purpose of this new phone number.
If you don't want to buy the credits regularly for that number you can use a post-paid service instead which can be paid with a credit card. If you still have another mobile phone that you no longer use then you can use it for 2FA SMS only for banking. You don't need a sophisticated smartphone, you can use an old school phone as long the mobile phone can receive SMS. That's all good.
In the following video, IT pros have a valuable discussion regarding the importance of using different phone numbers for your bank account.
https://www.youtube.com/watch?v=SNpphMz-w5w
3. To prevent identity theft.
The hackers have stolen your identity usually from your local computer, cloud or other 3rd party websites where you have submitted your important files. It's difficult to find out how strong the security system of 3rd party websites, it's better to be careful when you are submitting your sensitive files.
However, on the other hand, managing sensitive files on your local computer and the cloud is relatively under your control. If you need to store your sensitive files on the cloud, please use the Personal vault folder, please refer to point #3 in the following article regarding the importance of a personal vault folder.
However, if you prefer using the offline method to store your sensitive files then I recommend using a USB flash drive with a fingerprint. Most of the time, the flash drive will not be connected to your computer, and when there's a time for you to access the important files it requires fingerprint authentication.
https://www.youtube.com/watch?v=8An_XTrpW3M
More about advanced security tips can be visited here:
https://answers.microsoft.com/en-us/msteams/for...
DISCLAIMER:
There's a link above from the non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.