The following were your examples:
1A. I've been meaning to watch the movie, but I always forgot to 'till now.
1B. I've been meaning to watch the movie, but I've always forgotten to 'till now.
The original passages of text are grammatically correct if and only if they are still grammatically correct after you:
- insert "
watch the movie
" after the word "to
"
- delete
I've been meaning to watch the movie
- replace "
, but
" with a period (a full-stop or dot)
2A. I always forgot to watch the move 'till now.
2B. I have always forgotten to watch the movie 'till now.
Both are grammatically correct.
However, native English speakers would never say, or write, either of those sentences.
For one thing, till
is used only when quoting old sayings and old proverbs.
When you are using your own words, not quoting an old book, then you use the word "until."
All of the following are idiomatic in contemporary English:
I've been meaning to watch the movie, but
I kept forgetting about it until now.
I've been meaning to watch the movie, but
I kept forgetting to watch it until now.
I've been meaning to watch the movie, but
I forgot about it
I've been meaning to watch the movie, but
I forgot to watch it
People only say till
when they are pretending to be old-fashioned, as some kind of joke.