I am sorry but we do need to stress this – the forum does NOT log anyone out. It can not and does not. Login, user management,. registration… these are ALL controlled entirely by WordPress itself – or any membership or use access type plugin that might be in operation.
IF you are seeing your members being arbitrarily logged out then you do need to take a closer look at what other items may be involved. Simple:Press accepts whatever WordPress informs us is the logged in state of the current user. We respond accordingly.
WordPress allows you to set redirections on the login, logout and registration processes. If you have these set and they are not working then, as Mr Papa suggested, the chances are that something else you have active os overriding those settings and grabbing precedence.