Chosen Solution

whey does lid come off when pouring

It’s held on by friction. The easiest fix is to replace it for $6.24 http://www.goodmans.net/i/9471/univen-pe

Use a thin screwdriver or the edge of a table knife and spread the 4 little tabs on the edge a little further apart. After a lot of use, they tend to become flattened a little, and lose some of their grip.