We have in the past offered a 'testing center emulation' modes inside our PC FAA test prep software. This is because long ago, some small percentage of people were unfamiliar with or at least intimidated by basic computer usage. Per our more recent experience and internal metrics, the need for this has now long passed. As such, we are removing these features (or rather, not building them into new versions) of our test prep apps. They may already have been removed by the time you read this.
You presumably know how to use a keyboard and mouse, and so there's no reason to worry about the testing center experience. None. The test center software in use at all FAA testing centers these is very straight-forward and user friendly. Additionally, if you're really concerned, you can take a short tutorial on the test center software interface itself before you take your actual test. In writing this answer, we contacted about a dozen people who recently took their FAA knowledge tests. All but two two skipped the testing center interface tutorial and the two that did said that they did so only out of an overabundance of caution but really there was nothing much to be learned there.
In other words, the test center interface these days is a 100% non-issue.