Campaign Experiment Settngs
I want to do A/B testing with 2 different designs at the ad group level. However, the campaign experiment settings are for the campaign level. I am planning to split control and experiment groups by %50 / %50 but I don't want the other ad groups in the same campaign to be affected. Do I need to mark the ad groups that shouldn't be affected as "control only" with grey?
Re: Campaign Experiment Settngs
The adwords campaign experiments feature was not designed to split test designs on your website. You're not going to be able to make it work properly if you try. You've run into the first obvious problem already.
What you're looking for is Google Analytics content experiments. You can start here: https://support.google.com/analytics/answer/1745147?hl=en&ref_topic=1745207&rd=1
Hope that helped.