First of all, For me I saw a lot of "link" inside your diagram which seems to be use in a wrong way. Maybe you can take a look at some UML ressources and more specifically, association, generalization, include and extend links... BTW I am just curious to know which tool do you use for this? Visio or ArgoUML?
So now concerning your(s) question(s).
- When you want to associate an actor to an usecase you have to create an association between them not a generalization
- If you want to specifiy that an "manage profile" use case can include (or not) changing password, view its profile, etc for this I would use an extend link.
- For modelling the fact that an given use case mandatory include another one I would use include relationship.
- the creation of an "add bet" use case "exntended" by the other one would indicate that you have a lot in commmon between all this possible bet.
Please take a look at my screenshots and let discuss about it.