Giving Score should not overwrite manually updated scores. If you manually update a constituent's giving score you should be able to exclude from evaluation in subsequent runs.
"NOTE: Please keep in mind that if you have manually assigned a Giving Score to some of your constituent records, those records with manually assigned scores will not have their scores overwritten by the automated Giving Score process. The scores that have been manually assigned to those records will be respected."
If that's not working for you, you should probably reach out to support.
Although there are some suggestions to be able to only run giving score on a query of records.
I have been told by several support that running GS will not overwrite any manually changed scores. Score is just listed with the date, manual change is kept as current score. Is that not the case?
Ditto JoAnn -- at least that's what it says here:
I have been told by several support that running GS will not overwrite any manually changed scores. Score is just listed with the date, manual change is kept as current score. Is that not the case?