Oops, I forgot to attach the example.
Here it is.
#This file was created by <ingo> Thu Sep 16 16:54:01 1999
#LyX 1.0 (C) 1995-1999 Matthias Ettrich and the LyX Team
\lyxformat 2.15
\textclass article
\language german
\inputencoding latin1
\fontscheme default
\graphics default
\paperfontsize 12
\spacing single
\papersize a4paper
\paperpackage a4
\use_geometry 0
\use_amsmath 0
\paperorientation portrait
\secnumdepth 3
\tocdepth 3
\paragraph_separation skip
\defskip medskip
\quotes_language polish
\quotes_times 2
\papercolumns 1
\papersides 1
\paperpagestyle default
\layout Standard
In multiline equations sub-/superscript only works for integrals and not
for sums.
Example:
\layout Standard
\begin_inset Formula
\begin{eqnarray*}
& \sum ^{n}_{i=1}i & \\
& \sum\nolimits _{i=1}^{n}i & \\
& \int\limits ^{\infty }_{x=0}e^{-x^{2}} & \\
& \int ^{\infty }_{x=0}e^{-x^{2}} &
\end{eqnarray*}
\end_inset
\the_end
