When is it correct to say "I were....." and "I was.....". Most of us have probably said "If I were you....." but I wouldn't expect to say "I were going for a walk this morning".
"I were" is only used in the "subjunctive" form - a sort of imaginary mode, which most commonly appears after words like "if", or "I wish I were in Paris". . And even then it's more common today to say "if I was..." or "I wish I was".
I think there's some funny rule about use of the conditional tense matching the (otherwise) plural form of the verb with the singular person.
So ...
"I'd" (conditional tense) look it up "if" (conditional provision coming up) I were (plural form, usually used for first person plural, here being used for singular) you.
I think it's called the second conditional.
A text book gives the example "if I WERE you.." and refers to 'were' being used a sit's an impossible situation.
It then gives another example of the second conditional of "If I WAS the president I'd .." and describes this as an unlikley situation.
Maybe , then, I WERE is used only for impossible situations and I WAS is used for unlikely situations.
It just shows how complicated the English language is.
Not sure about that 'If I was the president...'
Usually, when we can say, but I'm not, after the If clause for example If I were rich (but I'm not) we use were instead of was. However, If I wasn't rich (but I am) needs the was. It's only this verb which this can happen to as none of the other verbs have two past verbs. ex. we use had for all persons
Seems to me it's largely a matter of habitual use, but the comments about the conditional tense are an interesting explanation. I'll try to think before I use 'was' and 'were' in future! Thank you all for your interest and answers.