Apologies for not answering your call, I am on a training course at work so no access to my mobile. Yes all working now...the email team recommended a password change as my current password had special characters in.( as recommended by Yahoo Mail) as part of my pass chance originally. All working on every device now.
I would like to thank everyone for their time helping me solve this problem.
Thanks for the feedback. I'm surprised that a password with special characters was possibly the issue - if that was the case the system wouldn't take those characters in the first place.
To me (as has happened in the past) is that a password change has effectively reset the account giving access. This is usually the case after doing a few password resets, causing the system to get confused (or trying an app/client too quickly after changing).