That's not recommended - and it's completely unnecessary if you know what you're doing.
1a) Game menu -> Graphics Options -> Animated Units: Selecting this option will turn on animated units. If you're playing a custom scenario, always turn this off I've yet to see an unofficial scenario that uses animated units.
1b) Game menu -> Graphics Options -> Animated Terrain: Selecting this option will turn on animated terrain. There is, however, a bug where one frame from the oil resource (desert) will be visible even when the option is deselected. You can solve this by dropping a dummy resource.spr file into your scenario directory (see
this thread at Apolyton). Use of this file will completely eradicate any interference from the Original game's resource.spr file - even if animated terrain is turned on.
If you can't change either of these options, it means that the scenario designer has disabled them via the animation lockout settings in the Cheat menu (see below). These Graphics Options, however, are universal and can be changed by switching to a game where they haven't been disabled.
2a) Cheat menu -> Scenario Parameters -> Edit Special Rules -> Terrain animation lockout: Disables the Animated Terrain option in the Graphics Options menu. Don't use it.
2b) Cheat menu -> Scenario Parameters -> Edit Special Rules -> Unit animation lockout: Disables the Animated Units option in the Graphics Options menu. Again, don't use it.
2c) Cheat menu -> Scenario Parameters -> Edit Special Rules -> .SPR file override: Blocks the static.spr file. Does not block animated sprites! If you don't use any static unit sprites in your scenario, turn it on.
3) Rules.txt -> @UNITS_ADVANCED -> .SPR file override flag: For each unit it will block both static.spr
and the animated sprite file (unitxx.spr). Setting all of these flags to 1 is a sure-fire way of completely eradicating interference from unit sprites in your scenario.