User experience / interaction design for elderly people using banking apps

We are currently designing a mobile interface for elderly people for the banking industry.

Is there a need for tweaking the standard (not applying the best practices, for example: tooltip for mobile)? Because they don't usually get something very quickly.

The data says that these are the people that let others use the functionality to complete a task, they cannot actually use products that are too cluttered - based on usability testing, they are easily overwhelmed with so much information all at once. What are the best practices we can use to actually help them understand/use a functionality better?

What would you recommend on designing such? Any inputs are very much welcome.