It is important to know how personalizations are copied from a source to a target in the tool. A personalization entity is the panel for the personalization and the personalization type. This is the smallest entity that you can manage in the tool. It is not possible to manage, for example, different conditional styles within a panel.
In the tool, you can selector to apply a personalization from a source to a target. is only enabled for program, user, and role. Merge to is only allowed for programs and personalization types on a specific panel.
Useif you are copying all personalizations from a source to a target, which removes any existing personalization that the target has. The Copy to function will apply the same personalization that the source has to the target.
will compare and only overwrite those personalization types that the source has to the target. If the target already has hyperlinks and you merge from a source that has a context publisher (and no other personalization exists), the target will get the context publisher but still keep the hyperlinks. There is no merge within a type. If both source and target have hyperlinks, the hyperlinks in the target is completely replaced by those in the source. To handle that level of complexity, you must edit the XML through export/import manually.
If you copy personalization from, for example, one user (source) to a role (target), any existing personalization of the same type in the target will be overwritten, not merged.