Enter this into your profiles chrome folder > userChrome.css file for tabs on bottom, tab width to label (pinned tabs at 94px width) and tabs multi rows:

/* Toolbars With Tabs On Bottom */

#main-window:not(#f) #PersonalToolbar {
  -moz-box-ordinal-group: 2 !important;
}
#main-window:not(#f) #nav-bar {
  -moz-box-ordinal-group: 3 !important;
}
#main-window:not(#f) #TabsToolbar {
  -moz-box-ordinal-group: 4 !important;
}
main-window:not(#f) .titlebar-placeholder {
  display: none !important;
}
#main-window:not(#f) #browser {
  border-top: 1px solid #9F9FA1 !important;
  margin-top: -1px !important;
  position: relative !important;
  z-index: 1 !important;
}

/* Tabs Width To Label */

#main-window:not(#f) .tabbrowser-tab:not([pinned]) {
  width: auto !important;
}
#main-window:not(#f) .tabbrowser-tab[pinned] {
  width: 94px !important;
}

/* Tabs Multi Rows */

#main-window:not(#f) #TabsToolbar[movingtab] {
  padding-bottom: 0 !important;
}
#main-window:not(#f) #TabsToolbar[movingtab] > .tabbrowser-tabs {
  padding-bottom: 0 !important;
  margin-bottom: 0 !important;
}
#main-window:not(#f) #TabsToolbar[movingtab] + #nav-bar {
  margin-top: 0 !important;
}
#main-window:not(#f) #titlebar-buttonbox {
  display: block !important;
}
.tabbrowser-arrowscrollbox scrollbox > box {
  display: block !important;
}
#main-window:not(#f) .tabbrowser-tab {
  -moz-box-sizing: border-box !important;
  min-height: 33px !important;
  vertical-align: top !important;
}
#main-window:not(#f) #titlebar-buttonbox {
  vertical-align: top !important;
}
#main-window:not(#f) .tabbrowser-arrowscrollbox scrollbox {
  overflow: visible !important;
}
#main-window:not(#f) .tab-label-container[textoverflow]:not([pinned]) {
  mask-image: unset !important;
}
#main-window:not(#f) .scrollbutton-up,
#main-window:not(#f) .scrollbutton-down {
  display: none !important;
}

Hi BIC1, if userChrome.css is not familiar, it's about 10 minute project to set up. I have a site with more info here: https://www.userchrome.org/

If you use the above style recipe, the 3 buttons on the title bar will be covered unless you show the menu bar or title bar. If you don't want to show either of those, alternate workarounds could be:

(1) Open an empty gap above the main toolbar

#navigator-toolbox {
  padding-top: 20px !important;
}

(2) Create empty space at the right end of the main toolbar

#nav-bar {
  margin-right: 106px !important;
}

The best measurements will vary depending on your Windows theme.

Also, In my last Firefox version I could click on the tab bar and it would open a new tab. Now it minimizes the window. Is there any cure for this?

Double-clicking the tab bar activates the behavior of double-clicking the title bar, which is to switch the window back and forth between "maximized" and "resizable". I don't know of a trick to change that, but perhaps someone else does.