html editor breaks existing records

we've updated to 6.0.5 and it seems that the html editor is enabled by default - this is making all existing records unreadable (no new lines) and anything containing <> tags, e.g. c++ template code examples to be unrenderable.

How do we swtich the editors to be text? (when we first observered a similar issue in an earlier update the provided solution was to switch the column types to varchar - however this work around seems to no longer have any impact, the column types are still varchar).

This have no effect at all even after cache cleaning...