Is it possible to increase the validity of access token for REST Apis

Hi,

1. Is there any way to increase the validity of REST Access Token? I suppose due to security reasons, the validity is set for 1 hr.

2. Refreshing Tokens

we configured the OAuth client as in the image below.

But when we are looking for refreshing tokens  

https://community.telligent.com/community/11/w/developer-training/63121/authentication#Refreshing_Tokens

code shows that client Id is Required. Since there is no way to store the user credentials is there any way we can refresh the token without the client secret