"Select Priority Topics" is not shown to reviewers

We want reviewers to be able to select their priority topics.
We tested the option but reviewers are unable to access it.
How can we let reviewers choose the topics they are most familiar with?

First, please check whether the option has been enabled under:
Overview => Settings => Main Settings for the Review Process
The option is called "Priority Topic Selection". It is enabled by default (see image 1).

Second, please go this page:
Overview => Settings => Conference Phases and Deadlines
... to activate the module and set the phase in the section "Reviewers Can Select Their Priority Topics" (see Image 2).

As soon as the option has been enabled, the reviewers can select their priority topics (see Image 3)