What browser are you using?  It is the browser that displays these
kinds of alerts in certain places, whether they originate from the
browser or the web page.  If you let the entire message speak and
don't interrupt it, you should hear choices with commands for them
like allow, alt a don't allow, alt d.  I made up those choices and
letters but I make sure to listen to all speech and pay very close
attention to the choices and commands.
I'm not sure if and how you see these things after they have spoken. 
If an unfamiliar message occurs, unless you know it is of no interest,
don't stop it and pay very close attention to see if any choices and
commands are given if the message is that kind of message.
Gene
----- Original Message -----
*From:* leochick78@... <mailto:leochick78@...>
*Sent:* Tuesday, December 03, 2019 10:39 AM
*To:* nvda@nvda.groups.io <mailto:nvda@nvda.groups.io>
*Subject:* [nvda] Accessing alerts on webpages

How does one access alerts on a webpage?  Like the would you like to
save this password alert or answer an incoming chat request on a chat
help page?

Thanks for any help,

Sarah