You can change the order of the Account Groups in the Settings > Accounts Grouping: 

'Settings' > 'Personalization' > 'Account List' > 'Account Grouping' > 'Edit Button in the upper right corner' > 'grab the group with your finger' > 'pull to the desired position' > 'Save'

Note:
Accounts, non-grouped accounts will always be shown on top under 'My Accounts'. This group cannot be relocated.