Max Date from related records help

I have a table of Customers and a table of memos which are related to the Customer by Account number and in the memos table I put a note each time I speak to the customer with basic info of the date the person I spoke to and what was said.

In the Customer table I would like to see the Max (Memos:Date) ie the latest date that I spoke to the customer. At the moment it shows me all the dates as I have used it as a lookup since I cannot find a way to get the Max from a related field as a date. Anybody have any ideas please. I usually use Filemaker and the relationships then are quite transparent so am struggling a bit

You want a rollup field (versus a formula field). Have the rollup use the aggregation formula MAX(values) on the {Date} field in the [Memos] table. On my computer, the place to select the field to rollup is hidden–I have to scroll to find it.