How can admins renew membership for members?

Hi. Is there no way for admins to be able to extend a member's subscription (say, adding a other year) as a freebie? I have searched and can't find how to do it at all.

I have even tried increasing the term in the subscription setting from 365 days to 365 weeks, but the existing members on that subscription still show as expiring at the same time as previously.

Please help.

Best wishes, Andrew.