Make sure you're using a WPLMS child theme. If you;re using WPLMS Blank child theme, then copy the header.php file from wplms theme into the blank child theme and follow below instructions.
1. Go to WP admin -> Appearance -> Editor -> header.php
2. search for the word "trigger"
3. Replace this code
<a id="trigger"> <span class="lines"></span> </a>
with this :
<a id="trigger"> <span style="color:#FFF;font-weight:600;">MENU</span> </a>
Result :
To change the Menu icon
<a id="trigger"> <span style="color:#FFF;font-weight:600;font-size:20px;line-height:1.5;"><i class="icon-menu"></i></span> </a>
Result :
