Increase Scrollback Buffer in Putty

I'm running Putty on Windows and can't find an option to increase the size of the scrollback buffer . It seems set at about 4 pages of text.

Am I missing something?

You can increase the scrollback by selecting the Window options category and changing the Lines of scrollback option.

First load the session, then go to the Window category in the left pane and change Lines of scrollback to say, 20000. Go back to the Session category and save it.

Note: you must load the session for it to save!

Its very simple load your required session and change your desired scroll back value on window option then click on Save button.