Hi there @katygirl, welcome aboard to our Community. Make sure the battery is properly inserted. I saw cases where the battery loose connection and might caused inaccuracies on your step numbers.
I think the post from @Rich_Laue, it might help you to review your Zip battery.
About fixing your already logged data, is not possible but you can add a manual activity to average your missing data. For more information and help, take a look at this other post for Manual Activities.
Hope this helps and don't forget to keep me posted.
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