Are you looking at the correct conversion rates for your goals?
You can calculate your conversion rate as both % of Visitors (Sessions level) and as % of Visitors (User level)
The conversion rate reports in GA use the Sessions level.
Which one you should choose depends on your conversion goal. “Is this something we want visitors to do every time they visit, or something we want as many visitors as possible to do?” For Ecommerce sites, look at Revenue per User
If you want to measure conversion rate at the User level, create segments and calculate the number of users in the Audience > Overview Report
The next time you set up an A/B test, a dashboard or a goal for re-design, think about which level you want to look at (Session or User).