"Contribution amounts section" checkbox setting on contribution pages always shows as checked.

When setting up or editing a contribution page, the user can choose whether to turn the 'contribution amounts section' on or off in the 'Amounts' tab of the contribution page set-up wizard. In the case of a page designed solely for membership sign-up, for example, it is essential have this section turned off.

However, I've found that if I do turn this section off by unchecking the checkbox, this setting is not remembered, and every time I return to the 'Amounts' tab when editing the contribution page, this checkbox is always checked regardless of what was previously set.

In my case, I've also seen that on contribution pages where I have turned this off, the live page includes the label text: "total amount" in cases where this is nonsensical (e.g. two membership types available only, so no addition of options is required).  Update: the appearance of the "total amount" text of the page was due to erroneous CSS on the site I'm working on, so this can be ignored.

I was able to repeat this problem on the demo WP site. I'm running WP 4.7.4 and CiviCRM 4.7.18.

Also noted on the same version on a Drupal site. For more see the StackExchange post at https://civicrm.stackexchange.com/questions/18362/how-do-i-turn-off-the-contribution-amounts-section-for-a-membership-only-contr/18365?noredirect=1#comment20489_18365