Advance setup activities are detailed in this article.
1. Reasons for advance can be updated in this table. If a reason has been used in a request it cannot be deleted.
2. You can select the roles which can initiate an advance request
3. There can be multiple levels of approvers and you can add these in the approver table. You can change the approvers at any point of time. These changes will be implemented on new requests, existing requests will not be changed
Remarks compulsory - if this parameter is activated then remarks are compulsory while submitting an advance request
To manage visibility of advance requests on mobile and browser refer to the article on Managing visibility of records.