Update unique vlues into same CF (unlike bulk update with common values), in many issues

We are required to update a unique value into a same Text CustomField but in many issues

Bulk update des common value update across many issues, but in our case, we need to update not common instead a unique value

For example

Issue1 FieldA txt-no-someuniqno.
Issue2 FieldA txt-no-someuniqno.

Is there an way to achieve this ?