Intellij undo history size, not much?

In Intellij settings the clipboard settings I have tried with are 999 and 9999 and 99999 but it still too short on undos.

I’ve failed to see what “clipboard settings” have to do with the “undo limit” (or with “undo” at all). Care to explain?

Local History is definitely the way to go here as it works across sessions, files, and whole folders — you can undo very complex operations in one click (e.g. replace/refactor in multiple files).

In any case: if Local History is to complex or you are a hardcore person who prefers to hit Ctrl + Z quite a few times in a row instead of few clicks with Local History, you can increase undo limit (which is 100 steps by default). For that:

• Open Registry (Help | Find Action... and type registry)
• Find undo.documentUndoLimit entry and set your limit to a higher number (e.g. 1000).

P.S.
IDE restart may be required.