Modify Search Creteria - dimmed

Question

I use saved queries a lot. After upgrade to PsE11 I find them harder to use.
How can I modify a saved search? Under "options" both "Save Search Criteria as Saved Search" and "Modify Search Criteria" are dimmed.
My saved search is built with "Advanced search", and contain a mix of included and excluded keyword tags.

Answer 1

Let's start with :
If I start a "single find" (the little rigth angle in the list of sub-categories/tags) from on "Boat" it finds all photos tagged with "Boat", and also those tagged with sub-categories or keywords under "Boat". The option "Hide bets match result" hides all of them. I wish there was an option "Show only exact matches" that would include those tagged only this "Boat" and exclude all photos tagged with a keyword or sub-category of "Boat". In this way there would be no need to maintain the saved search.
I agree, that's an important missing feature. The workarounds are far from being easy and involve assigning temporary tags to a lot of pictures, depending on your criteria.
From the rest of your description, I see you are mastering very well the handling of hierarchical keyword categories in Elements. As I see it, you have to  think about two problems :
1 - saved searches are dynamic. By changing the hierarchies, you change the meaning of older saved searches. In some cases, it would be necessary to assign a fixed keyword to the selected files if you change the criteria, even temporarily.
2 - Working with complex hierarchies in the categories is an organization process very different to the relational database system used with keywords, by combining logical operators. For instance, suppose you have no hierarchy under 'boat'. You'll have a keyword 'boat' and another 'sail ship' (same hierarchy level). That enables you to define a query with a combination of both keywords and operators like '.and.' / '.or.'  That organization is very flexible and is the reason why hierarchical database system are not chosen when you need to reorganize your data.
As an example, I have reconsidered a genealogy catalog organization. Instead of having keywords for branches of the family and one for each member, I assign several keywords : first name, name, birth name for women, nickname. If people are known with a first name or in a diminutive first name, I assign both to the person. I can easily find anyone depending on the criteria I can remember. No hierarchies, but if I want to see a full branch based on name or birth name, I can select them easily by a combination of keywords.
Further problem with the hierarchy in Elements : the hierarchy levels are categories, sub-categories, keywords. What if you want more, for instance if you are dealing with animals, species, sub-species and so on ?