why does firefox not let me open the ould yahoo mail ? i put the link in the startup custon url and it drops half of the custom i entered and the when i reopen the browser i get the same new mail

ok i asked this before and that did not help why does firefox not let me open the old yahoo mail ? i put the link in the startup custom url and it drops half of the custom i entered and the when i reopen the browser i get the same new mail. so i go to the settings and then to startup and then i click on custom urls and then enter the custom url https://mail.yahoo.com/d/settings/1 that is what i do in a new browser and that takes me to the old yahoo email back page and so i click the back arrow in that screen and it goes back the old yahoo email page. when i paste that custom url into the custom url field and it saves this mail.yahoo.com that take me to the new yahoo email page and that new yahoo sucks, it is about as worthless as gmail. so how do you save the actual custom url you need to save for the startup of fire fox. i'm about to go back the goggles browser at least that one opens all the correct pages i want to use. it does the same with ebay but at least ebay is set to open my watch list when i first go to ebay. thanks those crash reports may be form my other pc that crashes the tabs all day long. so i took that out of service for now and i will be reinstalling the os again to clear out the hd someplace on that pc is a bug so it seems i have to different profiles and i have tried to get one profile to use on both pc and that fails bad. but that will be another question after i get this figured out the photo are i think the 1st is what i want and the 2nd is what i;m getting after i save and see that is wrong i will reply to correct them if i do not reply then they are correct. thanks