confused on shipping charges

[dznypal55]

I sometimes estimate the shipping charge when I list an item

if the item sells through the ebay shipping to print labels 

I then put in the actual weight of the item

sometimes I dont need as much shipping material as I thought which 

then could lower the shipping cost

yet the shipping charges stays the same even though the package

now weighs less then when I listed it

also unreated question

whenever I would get a watcher on an item I then had the option so send them an offer

twice now I havent gotten that option

is there a reason

thanks

[tobaccocardyahoo]

If you enter the shipping charge as a fixed fee, it remains fixed. When you pay for postage, that does not affect what the buyer pays.

Are you using calculated shipping in your listings or are you listing a shipping fee?

[dznypal55]

I just double checked one of my listings and it said 

standard shipping which is what I think I always used

but then its says 

your listings with calculated shipping  now shoes discounted shipping to your buyers

now I never changed anything with shipping

at one time I did see something about calculated shipping to "select sellers"

but as far as I know Im not a selcted seller

so confused