Logging in using android

[#1]

There are a number of sites that I have no problem logging into when using firefox and Linux on a desktop computer but trying to log in using firefox on a android tablet I just get a message that the password or user name is incorrect.
Ebay and a energy company are just two examples but there are others.
Any ideas ?

[#2]

Try the new incognito tab first the try again.

[#3]

Incognito tab ? Where do I find that ?
1.  On an IPad
2.  On a Samsung galaxy.
Thanks

[#4]

Android 4.0.4 top right hand corner tab of the stock browser.

[#5]

Thanks but that does not appear on my list which shows,
Share
New tab
New private tab
Find page
Request desktop site
Page
Tools
Settings
Help
Cookie whitelist
Suspend/resume SDC
Undelete & Suspend
Bluebell firewall
I have tried the new private tab but still no luck

[#6]

That's because you're not using Chrome...
Have you tried another browser on the tablet to see if it's the same? 

[#7]

I was using Firefox but will have a go with chrome .

[#8]

New private tab=Incognito. Or cookies are off

[#9]

New private tab did not work but using chrome did .
Thanks for that.