Here are several ways for you to transfer assignments from one spectrum to another. This may be relevant to you, if you have imported chemical shifts from the BMRB and created a peak list (see the BMRB Import tutorial on how to do this) which you want to use as the basis for the peak list in the spectrum you recorded. Or you may have two spectra recorded under different conditions (e.g. with/without ligand, different temperature, buffer etc.) which means at least some of your peaks have moved and now you want to transfer the assignments from one spectrum to another.
You can copy a peak list from one spectrum to another (as long as the axes match) by dragging a peak list from the sidebar and dropping it onto a spectrum in a spectrum display module. A small pop-up will ask you to confirm the peak list you are copying and the target spectrum you are copying it to. Then the peaks will be copied. Now you can move the peaks to the new correct peak positions by dragging the peaks with the middle mouse button. It is then also worth making sure the peaks are in the correct position using SE (snap to extremum) or RP (re-fit peak with a Guassian fit).
This method of transferring your peak assignments is particularly suited to situations where your peaks have either not moved by very much, or only a few peaks have moved.
Alternatively, peak pick your new spectrum in the usual way (e.g. Shift + Ctrl/Cmd + left-drag over the whole spectrum - see the Peak Picking tutorial for more information). You can then use the macro shared here to copy the assignments from one spectrum to another (see our Running Macros tutorial on how to run a macro and link it to a user-defined shortcut). Simply select a peak in your original spectrum which has the assignment you want to copy and the peak in your new spectrum which you want to copy the assignment to (hold down Ctrl/Cmd to select multiple peaks). Now run the macro (e.g. with a user-defined shortcut) and the assignment will be copied over.
This method of transferring peak assignments is well suited to situations in which there are many large differences in peak positions and moving many peaks with the middle-mouse button can become a bit fiddly and tedious.
You can also make assignments by left-dragging an NmrResidue or NmrAtom from the sidebar onto one or more selected peaks. This could be useful if you want to make assignments based on a printout or table rather than data that you already have in your project. If you have made a mistake, simply undo it with Ctrl + Z (Cmd + Z on a Mac) or drag a different NmrResidue/Atom onto the peak. If you wish, you can select multiple peaks in multiple spectra and/or displays and drag and drop NmrResidues or NmrAtoms onto them all in one go - just make sure you do the drop on top of one of the peaks.
In some cases you may find that no assignment is made when dragging an NmrResidue onto a selected peak. This may occur when there is an ambiguity about which NmrAtoms in the NmrResidue should be associated with the peak. For example, a Trp residue contains a side-chain NH group (NE1/HE1) as well as the backbone NH group. In this case you need to drag the desired NmrAtoms onto the selected peak rather than the whole NmrResidue.
Note that if you have not selected any peaks, dragging an NmrResidue or NmrAtoms onto your display will place marks at the chemical shifts associated with the NmrResidue or NmrAtoms.