Okay, this is a very difficult sentence. Seems to be from psychology. I try to tear it into pieces in the hope that you can get the meaning better. Fähigkeit = ability Umstellung = switching over to/adjust to + fähig = being able to => adaptability wenig = less fest = strong/firmly + gefahren = driven (past tense) => stuck (literally like a car in the mud) or intransigent here. Persönlichkeit = personality Struktur = structure So: This ability indicates an adaptable and not very steadfast personality structure.