Hi Yetti,
As Welfarite has said, your Welfare Officer is not involved in your new disability payments.
It's not clear by your posts exactly whether you are changing to Disability Allowance or Invalidity Pension, but this should be detailed in the award letter that you received from Dept Social Protection, as well as the method which they intend paying you.
Either way you will need to contact the Dept Social Protection section that pay you, as they will have to post you a form to enter your bank details on & sign.
Your best bet would be to ring them on Monday.
Telephone 1890 927 770 or 043 3340000.
Ask to be put through to the Disability Allowance Section or the Invalidity Pension Section. Give the person your PPS number & they will be able to tell you exactly what payment you are on. Tell them that you want your payments to be put into your bank account. They will be able to transfer you to the right section & will post a form out to you to fill in your bank details, which you will have to post back to them.
It might take a week or two for your payments to go to your bank account, so you may need to go to the Post Office until it's sorted out, but don't worry - they will tell you exactly what to do. You haven't messed up at all - they will sort it out no problem.