Welcome to Vodafone Community
If the option is available to you as a new member then it'll be in......
Press your current avatar that will invoke a pop up box with various options.
The top option is My settings.
Then on the next screen use the 'v' where it says Username to bring up another set of pop up options.
Choose Personal Information.
At the top it will say Avatars.
If.you don't see it then put your phone in Landscape mode which if the option is available to you Tap on that and choose.
Current Phone > Samsung Note 9 _512Gb > Model: SM-N960 Hybrid-Duos.
Samsung One Ui / Pie.
Samsung Gear s3 Frontier Watch.