Which is the Primary key here? I assume "RefundID" as primary key .
update CI
set CI.[Description]='Dispute'
from [CustomerInfo] CI
inner join
(SELECT distinct top(10) * from [dbo].[CustomerInfo]
where [RefundStatus]='Dispute'
or [SynJobTimestamp]=null
or [ProcessOwnerID]=null
order by RefundID asc) [tmpCI]
on CI.RefundID=tmpCI.RefundID
It is advisable not to use order by in sub query . so the below query give best result ,
update CI
set CI.[Description]='Dispute'
from [CustomerInfo] CI
inner join
(SELECT distinct top(10) * from [dbo].[CustomerInfo]
where [RefundStatus]='Dispute'
or [SynJobTimestamp]=null
or [ProcessOwnerID]=null) [tmpCI]
on CI.RefundID=tmpCI.RefundID
If you have composite key ,or any other key ,change the condition accordingly .