I'm running KMM compiled from the git master branch today on Fedora 31. This has been a problem for a while.

In the KMM settings, Ledger section, Import tab I have set the "Match transaction within days" to 15.

This setting is ignored when importing transactions using direct connect which is how I import almost all of my transactions. I'm not sure when this setting is supposed to work but is does not work for OFX imported transactions using direct connect.

Instead is appears that KMM matches the transaction with the closest amount value no matter how long ago that transaction took place. This is the worst thing it could do for paycheck transactions since they have many splits and unless the matching is limited to fairly recent transactions it can match with a paycheck from years ago when the splits (such as gross pay) were very different. I have to delete the imported transaction, then copy a recent transaction and modify it to match the amount and then re-import it to match the one I entered manually.

At the very least the global setting should be functional with the most common way to import transactions, direct connect.

Ideally it would be possible to modify this setting on an account basis in the online banking settings under import details.