Adding rules for using keywords

I'm adding to a budgeting tracker and need your help!

I am tracking general spending - in one of the columns is a buzz word which will say Gary or Helen (depending on whose account). Separately I'm tracking remaining amounts for each that I would like to auto-update on the basis of the general spending part.

So, for example - the K column tracks the spender (keyword Gary or Helen) and the L column is the amount spent.
Separately, there are 2 cells that have the remaining bank balance for each. I want these cells to update when there is a purchase added. So if L10 is £20 and K10 is Gary, then £10 is automatically deducted from the "Gary remaining" cell.

If that doesn't make sense let me know - I'm no pro with Excel!

Separate query
We use an AMEX, in a separate cell we track amount spent on that. So I'd like a running total of amount spent on it. As above, the K column could have AMEX as a keyword, and L column is amount spent.

All the best,
Browne

Attach a sample workbook (not image).so that we do not have to manually key in your data to do any testing.

Make sure there is just enough data to demonstrate your need. Include a BEFORE sheet and an AFTER sheet in the workbook if needed to show the process you're trying to complete or automate.

Make sure your desired results are shown, mock them up manually if necessary.

Remember to desensitize the data.

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