Exam enrollment question

1- I do not see the local exam center as a possible option for the Ansible exam EX407 enrollment, the closest exam center I belive is "Riyadh- Saudi Arabia"

2- if I enroll against one exam center, would it be possible to change the enrollment later, the reason I am asking I am traveling and I might have time to do the exam in Tunis, however afraid if I click the enroll button, there is no return.

3- How flexible is the enrollment in terms of modifications of data/time/city?